A Study of Adaptive and Optimizing
Behavior for Electric Vehicles Based on
Interactive Simulation Gamesand Revealed
Behavior of Electric Vehicle Owners
ThomasTurrentine
Martin Lee-Gosselin
Kenneth Kurani
Daniel Sperling
Working Paper
UCTCNo. 130
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A Study of Adaptive and Optimizing Behavior for Electric Vehicles
Based on Interactive Simulation Games and Revealed Behavior
of Electric Vehicle Owners
Thomas Turrentine
Institute of Transportation Studies, University of California at Davis
MartinLee-Gosselin
ProgrammeInterdiseiplinaire
en Amenagementdu Territoire
Laval University, Quebec
et DeveloppementRegional
KennethKurani
Institute of TransportationStudies, University of California at Davis
DanielSperling
Institute of TransportationStudies
University of California at Davis
Davis, CA95616
Presented at the World Conference on Transport Research
Lyon, France, 1992
UCTC No. 130
The University of California Transportation Center
University of California at Berkeley
ABSTRACT
Electric vehicles (EVs)promisemajor improvementsin air-quality. But the limited
range and long recharge times of EVshave created great uncertainty about consumer
demand.Technical consUaint studies find good news, that 20-60 %of aH households in
the United States could substitute an EVwith 162 KMrange for one of their current
vehicles. In startling contrast, choice studies - based on the responsesof consumersto
hypothetical choice sets - find that limited range and long recharge are extremely
expensive drawbacksand forecast sales of a few percent or less of the yearly newauto
m~ket. Thesestudies have relied on meagerdata and not investigated the potential
revolutionary effect on the automobilemarketof the introduction of alternative fueled
vehicles.
To explore potential dynamics,wehave conductedthree linked studies: 1) a test drive
of EVs,natural gas, and methanolvehicles by 236 citizens in Los Angeles(with 11
post-drive focus group interviews); 2) purchase intention and range simulation games
(PIREG)and 3) interviews with over 100 ownersof EVs. In this paper, we focus upon
the methodsand results of PIREG,an interview gamingtechnique derived from the
CUPIG(Car Use Patterns Interview-Game) developed by Martin Lee-Gosselin to study
future automobileuse. The interview uses one weekdiaries of householdsand detailed
descriptions of a recent vehicle purchasedecision to create a realistic simulationcontext
for examiningthe potential substitution of several newelectric vehicle technologies.
Theresults demonstrateseveral dynamics.First, increased information and learning
experiencewill reduce uncertainty in the EVmarket, affecting stated preferences. In the
test drive, 76%of participants said their opinion of EVsimprovedafter a test drive.
Participants were surprised at hownormal the EVslooked and performed. Second,
householdswill consider adaptive responses to limited range vehicles, given the social
benefits of clean air. MostPIREG
participants were surprised at howeasily electrics fit
their travel needs; most werehighly receptive to EVsif the price were equal to that of a
gas car. Usingdetail diaries of their owncar use, participants proposedsimple waysof
adapting to limited range including swappingvehicles for longer days, opportunity
charging at workand in somehouseholdsincreasing the vehicle stock. In most cases,
householdspreferred occasional adaptations to moreexpensive, long range vehicles.
Finally, PIREG
interviews and electric vehicle ownerinterviews suggest that a multifueled household(gasoline and electric) will optimize the EVuse with significant fuel
cost differences. In somecases, the ability of householdsto shift vehicle use to the EV
wasso significant, that it mayoffset the higher initial cost of EVs.
Information development,experience, adaptive response and optimization are central
processes underlying the developmentof the electric vehicle market. PIREGinterviews
offer the most detailed understandingof these processes and the purchaseintentions
that will result. Whilethe market is uncertain for EVs, PIREGgamesand current
practices of EVownerssuggest that with the fight price incentives, EVscould become
the primary vehicles in households,used for a higher percentage of householdtrips and
VMTs
than a gasoline counter part in the household.
THE PROBLEM
Electric vehicles (EVs)hold great promiseto reduce urban air pollution, greenhouse
emissionsand diversify the fuels used in transportation. However,the short refueling
range and long recharge times of current EVshave discouraged any auto-makers from
investmentsuntil there are majorinnovationsin batter), technology.But there are no
1
guarantees that a miracle battery will comein the near future and investment money
will only begin to flow into developmentwith an initial market. A decision has been
madein California to proceed with developingan initial market to encourage
investment and competition.
Facedwith no sales data on electrics, there is tremendousuncertainty about the size of
the market for EVs. Consumersare experienced with long range vehicles which refuel
easily. Current gasoline vehicles offer refueling ranges of 200 to 350 miles range and
refuel in about 6 minutes. A few consumershave experience with diesel vehicles which
offer even greater ranges. A few drivers in Canada,Italy and NewZealand have
experience with compressednatural gas vehicles (CNG)having ranges of 50 to 200
miles. A few hundred CNGownersare experienced with slow refills of five to seven
hours at their residence. Electric vehicles are a sharp contrast, offering ranges of 50 to
110 miles, and recharging at stations in 30 minutes or moreand slow charges of 3-8
hours at home.
Onlya few thousand electric vehicle enthusiasts throughout the world have experience
with short ranges and long recharges, and allocating trips to either a gas or electric
vehicle. Enthusiasts have claimedthese ranges are sufficient for mostdriving, but their
opinions and experiences have been largely overlookedas those of a few zealots.
Mostmanufacturersbelieve these limitations eliminate EVsfrom the market. In fact,
they often note that EVswere a significant part of the marketearly in the century, but
lost appeal oncegasoline cars gained starter motors. This history is worthnoting, but it
must also be recognized that muchhas changedin the interim° Householdsoften have
two, three and four vehicles, specialized vehicles for recreation, commuting
and cargo,
moredrivers per household,increasingly complextravel behavior as well as a growing
concernfor controlling pollution.
Thelong range and quick refill of gasoline vehicles is a convenientattribute which
manufacturerscan offer on all vehicles regardless of the intended use; therefore tank
size is seldoman option. But the value of long range in tradeoffs with newattributes of
EVsis still unknown,especially given that consumershave not had an opportunity to
pick and choose for themselvesfrom different ranges, refill speeds, and home
recharging. Latent market segmentsmayexist for EVsin whichthe mix of attributes
are valued morethan gasoline. The problemfor those wishing to predict the market is
that consumersthemselvescannot usually tell us with any certainty what they need
themselves, seeing they have even less experience than do we with electrics to assess
needs and wants.
PREVIOUS STUDIES
Several studies in the United States, and one in Germanyhave looked at howthe
limited range and long recharge will shape the EVmarket (earlier studies included the
impact of expected diminished performance of EVsbut improved performance of
current electric vehicles diminishesthe importanceof that constraint). In the more
distant future, longer ranges arid quicker recharge times will perhapsbe available, but
for the comingdecade vehicles will have ranges of about 162 krn and slow recharge
times of several hours and fast recharges of at least 30 minutes.
As a result of the limited range and long recharges, all studies have assumedEVsfit
only a two car householdwith travel habits for one vehicle less than the estimated range
of current lead acid battery EVs.Kiselwich and Hamilton(1982) estimate that 57%
households in the United States could accommodate
a vehicle with eighty miles of
2
range, Deshpande(1984) estimates that 60%of householdsdrive less than 96 miles 348
days per year. Greene(1985) estimates that 20-50 percent of vehicles are driven under
100 miles per day. Thesefigures suggest a sizable potential marketfor limited range
EVsin the United States.
In the UnitedStates, technical constraint studies find that range is so minimala
constraint, that recent studies (Nesbitt et al 1992)are focused moreuponthe
constraints of recharging requirements, such as house ownershipand having a logical
piace to recharge. Nesbitt et al estimate 28%of householdsin the UnitedStates could
meet these constraints. Fewerhouseholdsin Europehave two vehicles. A constraint
study by Hautzinger et al (1992) finds a market for 5 million EVs(approximately
of households) in former WestGermany.But car ownershiptrends indicate that per
capita car ownershipis headingin the direction of the UnitedStates (Shipper et al
19’92).
Thecomplaintabout technical constraint studies is that the real constraint on EVsales
will not be the physical constraints of householdtravel and infrastructure, but rather the
preferences of car buyers; that consumerswill not give up unlimited range or quick
refueling. Stated preferences surveys have supportedthis idea quite forcefully, and
estimate very low percentagesof vehicles sold per year.
In the absence of sales data on EVs, market researchers have used: 1) focus group
studies to explore potential preferences, 2) quantitative studies whichestimate market
shares of EVsfrom purchase data in the gasoline market and 3) stated preference
studies in whichsurvey participants makehypothetical choices from sets of car
descriptions. Focus groupsoffer insights but no numbersand studies of the gas market
use. irrelevant data. Thestated preferenceworkis mostinfluential.
Stated preferences studies report very high disutilities for limited range. Twoinfluential
studies were donein the late seventies. If adjusted for I991 prices, for a range of 50
miles in contrast to 200 miles, Mortonet al (I978) found a disutility of $10,000
Beggset al (1981) founda disutility of $ I6,250. In a very recent study, Bunchet
(1992) found a high aggregateddisutility of $15,000for similar differences in range.
a slightly different study, in whichindividual utilities werecalculated for each
participant, Calfee et al (1986) founda widerange of disutilities but manyin the range
above, even for consumerswhosaid they wantedan EVanyway.These disutilities
project very low probabilities for purchase.
The assumptionsof these methodsmust be questioned; for radical newproducts, stated
preference studies probably measureconsumeruncertainty morethan preferences. In
this case, they measureuncertainty about electrics, exaggeratedagainst the long term
experience consumershave with gasoline vehicles. Just on the issue of range
preferences, the participant has no idea howto evaluate limited range becauserange is
not a normalattribute for consideration. Manyparticipants in our studies don’t know
the range of their current vehicle. Consumers
are uncertain about the reliability of new
technologyand the stability of public policy and support for electric vehicles. Under
these conditions, stated preference studies are subject to large potential data errors; they
inappropriately calculate utility values from uncertain and volatile opinions.
Stated preference studies can measurepublic opinion, identify widespreadbeliefs about
AFVs,and mayhelp to identify potential hot-spots in sales for planning purposes, but
consumertastes, knowledgeand understanding of EVsare as yet undeveloped. There is
a greater need to pursue the constraint approachwith an eye on the processes which
will lead to diffusion of AFVs.Theemphasisshould be upon identifying potential
market segmentswhichcan be targeted by governmentpolicy. Identifying these
marketsrequires innovative research to simulate householddecisions in a yet
undevelopedcontext.
RESEARCH APPROACH
Diffusion studies have demonstratedthat learning processes are a critical dynamicin
the spread of newtechnologies. Wepropose that these learning processes can be further
identified as information acquisition, adaptive response, and optimization. While
diffusion studies have focused uponthe bundledproperties of a single innovation,
economicstudies have movedto analysis of particular attributes of products. Weadopt
this attributional perspective and combineit with diffusion studies to investigate how
consumerswill learn about and evaluate EVattributes for purchase, adapt to limitations
and optimize benefits. EVsalso have social benefits, whichwilt makevehicle
purchasesan increasingly political and cultural decision, nevertheless constrained by
the transportation needs and budget of a household.
Nesbitt et al (I992) assumedthat a major constraint on the near tem~market for EVs
wouldbe the infrastructure needs of households. Theyassume that only homeowners
with a safe recharging location wouldbe likely to purchase EVsin the early market.
Given this newconstraint, they found about 28 million householdsin the USand
(approximately1.4 million householdsin Los Angeles) could practically substitute
EVfor one of the vehicles in their household. These householdsare homeowners,with
a reliable place to recharge, and have 2 or morecars, and don’t drive both cars more
than seventy miles per day.
Werecruited 236 households in the Pasadenaarea of Los Angeleswhomet the criteria
of Nesbitt et al and a earned a householdincomeof at least 50,000U.S.dollars, (this
incomelevel is average for householdswhopurchase newcars). Theseparticipants testdrove electrics, methanoland compressednatural gas vehicles. Participants answered
questions before, during and after inspecting and driving vehicles° Wealso held 11
focus group interviews one weekafterwards for in-depth responses to test-drive
experiences and public policy questions.
While the test drive allowed us to improveour understanding of consumerresponses to
the driving characteristics of EVs,wealso devised a Purchase Intention and Range
Evaluation Game(PIREG)to investigate in a moredetailed waythe responses
households to EVsof various ranges and recharging possibilities. PIREGwas derived
from CUPIG(Car Use Patterns Interview-Game), aa interactive interview gaming
technique developedby Martin Le-Gosselinto investigate future car use patterns.
Households have minimumof $ 50,000 annual income, owntheir ownhouse, have two
(36 %of UShouseholds in 1988) or three vehicles (21%of U.S. households in 1988),
two or three drivers, all vehicles of 1985+vintage, and have purchaseda newcompact
car or mini-van in the previous year. Eachhouseholdkept one weekdiaries of all
vehicle use, whichweconvertedinto a single time-Iine chart for easy visual reference
during the interview. Householdsalso describe in somedetail howan whythey
purchasedtheir newvehicle.
Thehouseholdswere then interviewedat their residence, with all drivers participating.
A chart of their previous weekof driving and a gameboard are used to simulate the
substitution of EVswith various ranges, recharging schedules and opportunities into
their previous week. Participants were presented sequentially with two different ranges
4
(120 kin; 240 kin), slow (6-8 hr.) and fast (30 minutes) recharging abilities, home
awayfrom homerecharging locations and finally fuel-ceil technology (120 kmrange,
minute exchange). The householdis able to comparethe impact of each type of
technology in the context of previous experiences, and makedecisions about which
technology they preferred, given price differences for simple and advanced
technologies. Further gameswere played in which the household membersreallocated
trips to optimizetheir use of their electric vehicle, promptedby increases in gasoline
prices. Wehave completedseven of forty planned interviews and offer some
preliminaryresults fromthat study.
Afinal project was designed to view howhouseholds will adapt to EVsover a longer
period of ownership. Over100 hundredownersof electric vehicles in California were
interviewed about howthey have been using electric vehicles. Theseinterviews are in
the final stages of completionand we have begunpreliminary analysis, looking at
frequenciesfor the fu’st 76 interviews.
RESULTS
Participants in the drive test reported that their prior knowledge
of electric vehicles
c~:mefrom news media (89%) and consumermagazines(37%). After the drive test,
76%said their opinion of EVsimproved,indicating that the public mediais
underestimating EVs.Participants said in focus interviews that they had expected EVs
to be egg shaped prototypes or golf cart like. The performanceand normalvehicle form
of the EVswasa pleasant surprise for a majority of participants.
Eventhough participants expected EVsto have less performanceand be less practical
themthe vehicles usedin the test drive, electric vehicles werefavoredprior to the drive
in at least two ways.First, they werethe most familiar alternative fueled vehicle to the
participants; 95%had heard of electric vehicles (methanol 83%,NGV54%).
Additionally, whenasked prior to the test to select whattype of alternative fueled
vehicle they wouldlike, 54%selected EVs, with the remainder split amonghybrid
ele, ctric, hydrogen,methanol,CNG,and ethanol. Theprimary reason for this choice
wasair pollution and fuel security°
Learning about Range and Recharging EVs
Wlhilewell knownand popular as a solution to air pollution, consumersdo not
understandrange and refueling issues. Their lack of understandingleads to conflicting
intentions. In the study by Calfee et al (1985), manyparticipants seemedto
irrational, on the one hand choosingEVsover other vehicles, but insisting on range
needs beyondthose of the EVs.
Consumersdo not have a good idea of howthe range limit will "affect them- when
questionedabout range, they fall back on the range of their gasoline vehicle for
reference. Beggset al reported in their 1980study that participants offer the range of
their current gasoline vehicle as the range they needed. Participants in our focus groups
respondedin the sameway. Somedid not knowthe range of their current vehicle, but
said that whatever it was, that is whatthey need°
Weasked participants in our post test-drive focus groups to reconsider range needs
after calculating their last weekof driving. After reflection on their actual driving,
participants changedthe waythey calculated the range they wanted. The changes were
somewhatsystematic and lead to a two part calculation, a twenty mile safety buffer to
reraain on the vehicle at all times, and a secondusable range amountto the perceived
maximum
normalday of travel. In all cases, range needs dropped. Furthermore, the
sameparticipants were willing to trade awayeven morerange for simple fuel cost cuts.
Our PIREGinterviews demonstrated the same dynamics. Householdswere able to
calculate range needs in the light of one weekdiaries and two hour discussions of
householdtravel needs. The range values of these consumersare extremely volatile.
These dynamicscast immediatedoubt on the conclusions of survey studies in which
opinions are asked of participants whohave no experience with EVs.
Participants were offered instrumentation on a hypothetical EVwhich gave themthe
remainingmiles on a charge and not the remainingcharge as a percentage or fraction of
charge. Wehave no evidence that manufacturers will offer such instrumentation, but
our research wouldsuggest it wouldimproveacceptance. After discussing in some
detail the emergencyand normalneeds of these seven households, fourteen of the
sixteen drivers estimated their absolute minimum
spare range for an electric car to be
twenty miles. This is the amountof charge they wouldalways want on the car, even ff
returning home.The primary reason was for emergencies; everyone in the study lived
within a few miles of a hospital, but wanteda safe range for problems.
The 20 mile safety buffer figure is somewhatsurprising given current refueling
practices. Drivers in our PIREGinterviews report running the fuel level of their present
gasoline vehicles clownto different levels. Of the sixteen persons interviewedso far in
PIREG,twopersonsrun their tank until the fuel light turns on, four to I/8 of a tank,
eight to 1/4 of a tank and 2 refin at 1/2 tank. Whenrefueling, the majorityfill the tank.
Onlytwo teenage participants report refueling a small amountof fuel, spendinga
percentageof cash in their pocket.
Agehas an obviouseffect on participants willingness to risk running out of fuel. Four
persons prefer to go as manymiles as is possible betweenfill-ups. Oneperson watches
their trip meter and fuel light. Noone knewhowmuchfuel wasleft in the vehicle when
the red light wenton. Thesepractices suggest that mostdrivers are using about 3\4 of
the range of their tank on normalrefueling practices.
The second componentof a households’ range needs is composedof commutingneeds
plus a well knownset of trips\ activities whichoccur on a regular basis such as once per
monthor week, within a familiar radius from work. Only a few households experience
emergencies which require them to travel beyond this normal maximum
range. There
were business people whomust be prepared to respond quickly to needs outside their
normaldriving areas. Familyemergenciesoccur in near radii, if beyond, were
accommodatedby switching vehicles.
In contrast to the seeminguniversality of the 20 mile buffer figure, drivers in the
PIREG
study differed in their ability to estimate their rangeneeds. At least half of the
drivers overestimatedaily range needs in their diaries; only a few calculated evendaily
commutedistances with reasonable accuracy. Participants were moreconcerned with
times than distances. Therange of their vehicles is not a dally concern.
In contrast, planningto avoidrunning out of chargeis a normalactivity for the electric
vehicle ownerswe interviewed. Becauseof this planning and as a result of the minimal
needs for range beyondtheir electric, they seldomdrain their batteries (all rely upon
lead acid batteries, and have ranges from 30-100miles). Initial frequencies from our
sampleshowthat only 14%of EVownersdrain their batteries, while 71.4 %prefer to
top off batteries. 43 %said they toppedoff to save the batteries, 26 %said they topped
off to maximizepotential range. Only 10 %said they allowed the vehicle to go to 1/4 of
a charge.
Commutingand Electric Vehicles
Electric vehicles have long been considered special purpose vehicles. Researchershave
suggested an EVcan substitute as secondcars - although no precise definition as
second car existed except as a "lesser importancevehicle". This designation mayhave
followedstereotypical beliefs about the car used by married women
in families, as well
as buyingpatterns in whicha first car is the newestand most used while the secondis
older and less used. Changesin women’sworkpatterns and increases in car use have
outdated this stereotype.
Another segmented concept has been that of a dedicated commutevehicle. Commutes
are fixed distances and researchers assumemanycars used for commutessit for the
entire evening and thus are available for recharging. The average round trip commute
distance in the USin 1985 was24 miles suggesting a large numberof potential EV
users. A 1989 survey of commutersin Los Angeles finds that 77 %of the population
commutesless than forty miles round trip. Fifty-seven percent commuteon surface
streets while 36 percent commuteprimarily on freeways (SCAG1989)o These figures
suggest that the vehicles being used for commuteare an excellent market.
Nearly all the vehicle-driver-use patterns we have examinedinvolve somesort of
commute.But our workreveals the importance of other regular and extended travel
behavior built around the commute,workplaces, and homes.A closer look is needed to
assess howcommute
lends itself to EVacceptability. In our test drive samplein
Pasadena,wefound that commutedistance had little influence over attitudes or
purchase intentions, in the context of a choice betweena CNG,EVor Methanol
vehicle. Very few persons in our sample had commuteswhich exceeded the range of
EVs.Westratified our sample according to commutedistances: 27.3 %did not
commute,30.6 % commuteunder 20 miles round trip; 15.9 %commute20~40 miles
round trip; and 16.4 %commutedover forty miles round trip. Equal percentages from
these groups expressed purchase intentions for the limited range EVsover the unlimited
range methanol,vehicles.
Commute
distance did not influence choices betweenAFVswith different driving
ranges in the drive test. But in PIREG
interviews, the vehicle householdschose as a
potential EVfrom their householdfleet wasa commutevehicle, and its uses as a
commutevehicle were the primary object of discussion by the household. Travel
choices for workjourneys, shopping,recreation and other activities are built uponthe
commute;it provides the underlying structure for most travel choices during the work
wee, k. Thedistance of the commuteseldomstrains EVranges, but the residual range
after the commuteshapes additional choices and adaptive responses. Commute
does
figure prominentlyin the uses of current EVs.Our sample of current EVowners
contains a sampleof 38 commuters;31 use their EVto commutewhile 7 use a gas car.
Planning, Predictability and Recharging
In post-test drive focus groups, manyparticipants discussed flexibility as a basic want;
their need for unlimited range wasa "lifestyle" issue; they wantedthat freedom.
Anothergroup of participants stated less needfor unlimited range; their travel behavior
is moreroutine. In a survey of Los Angelescommutersonly 20 %say they stop on their
way to work, and only 30 % say they stop on the way homefrom work (SCAG1990).
The distinction betweenthose whorecognize their routine and those whodemand
unlimited range for their lifestyle maybe related to life-cycle and age. In focus groups
and test drive participants, those whoprofessed routine were mid-aged. This may
account for the finding that the mostreceptive to EVsin the test drive werein the age
category 45-55. In this group, night-time recharging wasa reasonable requirement,
their cars were seldomused during the evenings. Youngerdrivers considered unlimited
range a need in the evening and suggested they could not always count on recharging.
In all PIREGinterviews thus far, the amountof time the vehicle is parkedexceedsall
recharging needs, especially considering the vehicle is seldomused for its maximum
range, thus recharge times are relatively short. In the interviews, weoffered participants
a very slow hypothetical recharging rate of one hour for each ten miles of range.
Only on a few occasions at workplaces was a need found for faster recharge, caused by
errands or business needs. Participants in PIREGstudies had a goodidea of what
errands were done from work. Excessive variation and unpredictability in travel range
was found only in two households. Thus we find that more important than commute
distance wasthe perceivedand actual degree of routine in the travel patterns of
participants and their households.Theissue of routine wasrelated also to perceptions
about eveningactivities.
Adaptations to llmited range
For somePIREGparticipants, homerecharging provided for all range needs, especially
for vehicles that are used primarily for commuting
and not other activities such as
weekendexcursions. Thesehouseholds share vehicles often and the homeis the hub for
most activities. Whenpotential range conflicts are encountered, recharging at work
places and swappingvehicles with other household memberssolved the problem with a
minimum
of disturbance. Figure numberone is a chart of howone of the households in
a PIREGgameresponded to using a vehicle with one hundred miles range. Home
recharge represents what would have happenedin the previous weekwithout adapting.
Note the commuteis no strain on the charge, but business trips from the workplace use
all the charge. Thedriver of the car could haveeasily swappedcars with his spouse that
day, but preferred charging at work. This couple was confident they wouldpurchase
electric if available.
In other households, limited range mayrequire someadaptations in householdtravel
behavior; the amountof adaptation depends on travel needs. These primary adaptations
which we offered as solutions to problemsencounter in PIREGinterviews were car
swapping, opportunity recharging and 30 minute fast charges. Householdswere given a
hypothetical limited range vehicle and asked to substitute it into their previous weekof
activities (we offered a limited range to intentionally cause someproblemsin
completingthe previous weekstravel).
Vehicle swappingwas the most effective strategy to solve problems. Only in one
household did swappingvehicles not work- and the reason was not a direct range
conflict but a systematic uncertainty about range needs related to business demands.
Moreover,in manyhouseholds, swappingis a normal practice.
But there was resistance amongsomeparticipants to increased vehicle swapping;the
concerneddrivers identify strongly with the performanceand styIing characteristics of
their vehicles. Vehicles of teenagers were unavailable for swappingfor these reasons.
Therelatively infrequent need to swapand potential opportunity charging reduce
anticipated swappingand loss of one’s personal vehicle for the day. Opportunity
rechargingmet little resistance as a strategy. Mostvehicles in the study are parkedfor
long periods in potential charginglocations such as parking lots at work.
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At least two householdswere not potential limited range users, despite fitting our
marketsegmentcriteria in all other ways. Theseparticipants use their vehicles for work
purposes which mayinvolve unplanned excursions during the day. While such
excursions are rare, the primary problemis that they are important enoughto require
unlimited range. Planning, by swappingvehicles with another household memberwas
not feasible. Theremainingvehicles in the householdwere not easily replaced by EVs
becauseof their special uses for recreation or other duties or becausethe purchase
pattern of the householdwasto retire fu’st vehicles to a secondvehicle (here wedefine
second vehicle as an older vehicle). The daily schedule of these two vehicles involved
trips of such frequency that recharge at workplace was untenable, and whensuch
unplannedexcursions were required, they involved an accelerated schedule; a quickcharge of even twenty minutes duration wasuntenable. Theseparticipants could only
use EVsif equippedwith fuel-cell technology, which could be recharged rapidly by
fuel exchange.Thesecases demonstratedthat different EVtechnologies will attract
different market segments.
Anunexpectedresult of the PIREGinterviews wasthat two households chose not to substitute
an EVfor one of their current vehicles and instead said they were most likely to purchase an EV
as an additional householdvehicle. Thesehouseholdswere affluent and distinct from other
householdsin that they ownmorevehicles, including recreational vehicles and pickups.
Apparently these household devote a muchhigher ratio of household incometo maintaining
larger householdfleets; addingvehicles to their fleet is not unusual. This strategy
agrees with attitudes in the larger sampleof drivers in Pasadena.In that samplewe
foundthat the higher the numberof vehicles in a householdthe better its attitude
towards EVs.In addition, householdswith morespecialized vehicles, such as four
wheeldrive were morelikely to express an interest in EVs.
Optimizing use of the EV
Technical constraint studies have assumedsomeadaptive behavior by EVowning
households, proposing substitution of the least used vehicle in a householdwith an EV.
In the previous sections weshowsthat it maynot be the least used vehicle, but rather
the vehicle whichis mostpredictable. In this section weproposethat in somecases,
whereEVSfit the travel patterns of a householdparticularly welt, householdsmayeven
shift moretravel to the EVto take advantageof its other features, such as lower
operating costs, starting characteristics and convenienceof homerecharging.
The final round of the PIREGinterviews involves motivating householdsto use their
EVas muchas is possible° In somegamesthis was accomplishedby rationing gasoline
so that they wereforced to either combinetrips or use their EV.In other interview
gameswe raised the price of gasoline to $ 5 per gallon (American).Participants then
were given the opportunity to reallocate trips from the previous week. Theincrease in
gasoline was a significant motivation and inducedhouseholdsto shift a significant
portion of their travel to the EV.Householdswere able to shift travel to EVsbecause
prior to the price switch, the amountof range used by the EVwasonly a fraction of the
total range. In mostcases, after a price rise, the EVswitchedfrom beingthe least
utilized vehicle to the mostutilized vehicle in the household.Figure two is a
comparisonof VMTs
betweencar one and car two for a weekof driving. Figure three is
howthe couple reconfiguredtheir driving after gasoline wasrasied to 5 dollars per
gallon.
Whilegas rationing arid steep rises in gasoline prices wasused in the PIREG
interviews
to stimulate participants to shift gasoline use to EVuse, this motivationmayoccur
routinely in householdsas a result of the normalfeatures of EVs. Among
the EV
10
Household # 4
Week use of vehicle
1 & vehicle
2
lOO
90
8o
7o
6o
sO
4o
3o
2o
10
0
Tue~y
Figure 2.
Household# 4
$ 5 gasolineand vehicle # 2 is electric
lOO
9o
8o
70
60
5o
4O
3o
20
~o
0
Tues~y
Figure 3.
ownersweinterviewed, over one-half identified the EVas their primary vehicle, and
this was arnong hobbyists, manyof whomare using unconventional vehicles. The miles
driven per year of EVsin these householdswasequivalent to that of their gasoline
vehicle. If welook only at vehicles in this samplewith systemsof seventyvolts or
more, the percentagesof use rises.
Whilemanyof these current users are EVenthusiasts and not representative of the
general population, their reasons for optimizing the use of their EVare most frequently
economic,a feature that will affect the general population as well. Theoperating costs
of the EVare so low, and refueling is so convenient,that these individuals are
motivated to use the EVfor most high frequency journeys. Several EVowners have
even shifted to renting gasoline vehicles for out of range driving, to further reduce
costs.
CONCLUSIONS
In this study weuse an interactive research method,PIREG,in conjunction with
product testing and survey methodsto gain a broader understanding of the comingEV
market. In particular, PIREG,allowed us to test hypotheses about howhouseholdswill
changetheir current travel behaviorin responseto electric vehicle options and price
environments. The PIREGinterview both educates the consumerabout the utility of
future options and educates the researcher about important details in the consumer
household which affect choice outcomes.
The limited range of EVSand tong recharge times have been major blocks to the entry
of EVsinto the market; it is feared that they cannot competewith gasoline vehicles.
Becauseof the range advantage; consumerswill want unlimited range even if it is for
infrequent journeys. Stated preference studies confirm this suspicion. However,
constraint studies find that a significant percentage of householdsdo not needunfimited
range, even though their current vehicles have unlimited range. Moreover,most daily
travel of all vehicles is well within the rangeof current EVs.Also, citizens are realizing
the need for cleaner vehicles; and affluent citizens express a willingness to experiment
with limited range electric vehicles.
Theseare influences whichcould push the market either way. If we believe EVsare
goodpunic policy, citizens should be rewardedfor buying and using EVs. If given
proper price incentives, these householdswill find EVsto be advantageous,and
discover from other EVownersthat adaptations to the range limits to be minorissues.
In fact, if the operating costs are different enoughfrom gasoline vehicles, many
householdswill makethe EVtheir primary vehicle, using it for the bulk of household
driving chores, and using the gasoline vehicle for long distance trips .pn 12
and trips whichmust be madeat the sametime as the electric.
Householdoptimization of EVsmakesgood sense if your goals are to replace vehicle
miles traveled, or percentageof householdtrips currently taken by gasoline vehicles
with vehicle miles traveled by EVs.First generation EVswill be expensivevehicles. If
they function as the primary vehicle (defined here as percentage of VMTs,and trips)
could justify a higher price. This wouldmeana greater air quality impactper household
and wouldpromotetheir general utility.
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