Better Fuel Economy.
Every Truck.
™
10 Tips To Maximize Fuel Economy.
ISX15 Engines.
10 Tips To Maximize Fuel Economy.
Vehicle Spec’ing.
1. Spec gearing ratios properly.
For long-haul engines up to 450 hp (336 kW), recommended gearing for the ISX15 is
1370-1450 rpm at 65 mph (104.6 km/h). If less than 1650 torque, gear at 1400 rpm. For
1650+, gear at 1370 rpm at 65 mph (104.6 km/h). (See your Cummins rep for optimal ratio.)
For ISX15 engines 450 hp (336 kW) and above, recommended gearing is 1400-1430 rpm
at 65 mph (104.6 km/h).
2. Spec advanced aerodynamics.
An aerodynamic truck-and-trailer configuration versus a non-aerodynamic configuration can
result in a fuel economy improvement of approximately 13%.
Driving Habits.
3. Lower drive speeds.
At interstate speeds, each 1.0 mph (1.6 kph) increase = 0.1 mpg (0.04 km/L) loss.
For example, driving at 65 mph instead of 75 mph can save 1 mpg (0.43 km/L).
4. Run in top gear more than 90% of the time.
Every 10% drop of time in top gear = 0.5% mpg (0.22 km/L) loss.
5. Turn on Load-Based Speed Control (LBSC).
Using LBSC with aggressive settings of 1600 rpm can save as much as 3% in fuel.
6. Decrease idle rpm and idling time.
Using the lowest idle speed possible helps reduce fuel use by up to 0.5 gal/hr (1.89 L/hr). Every
hour of idle time that you eliminate can raise your vehicle’s fuel economy by as much as 1%.
7. Follow proper driving habits.
Sudden braking, rapid acceleration, downshifting too early and other poor driving habits can
negatively impact fuel economy by as much as 30%. Following proper driving techniques is
critical to maximizing fuel economy.
Measuring Fuel Economy.
8. Run 50,000 miles (80,467 km) before measuring fuel economy.
Early results are not an accurate representation. Tire break-in and effects of first fill can skew
the results.
9. Adjust for seasonal variations.
Seasonal fluctuations from winter to summer can account for a gain of 8% to 12% in fuel
economy. A comparable decrease happens when going from hot weather back to colder
temperatures.
Vehicle Maintenance.
10. Tires and maintenance are critical.
Tire tread and casing design can account for 12% difference in fuel economy. Proper
chassis alignment and tire inflation are critical to getting better fuel economy.
Key Electronic Features And Parameters
That Optimize Fuel Economy.
Load-Based Speed Control.
LBSC is a Cummins-exclusive feature that limits the engine rpm when not needed – to save
fuel and reduce driveline wear. When needed, LBSC will allow the engine to operate at the full
governed speed when operating with heavy loads and/or on moderate grades, or when making
gear changes. LBSC encourages proper driving techniques and improves fuel economy.
Gear-Down Protection (GDP).
GDP helps maximize running the transmission in top gear. This will keep the engine operating at
lower rpm for better fuel economy and engine life. GDP can be used in conjunction with LBSC to
limit engine operating speeds throughout the vehicle’s entire operating range.
Road Speed Governor (RSG) And Cruise Control.
Setting a lower road speed limit improves fuel economy. Using cruise control to maintain a
desired road speed (eliminating throttle input variance) also improves fuel economy. Road speed
governor can be set independently to encourage cruise control use.
Idle Speed Control.
Lower rpm settings reduce fuel use in all idling situations. Use the lowest idle speed possible.
Front-End Spec’ing.
Each spec’ing option and parameter setting can optimize the fuel economy of new
heavy-duty vehicles.
Spec’ing Option/
Parameter Setting
Approximate Gain
Aerodynamic truck vs.
non-aerodynamic truck
12%
Differential gearing
3%
Direct transmission vs.
overdrive transmission
3%
Fuel-efficient tires vs. standard tires
8%
Load-Based Speed Control usage
3%
Gear-Down Protection usage
3%
Fuel Economy Savings.
Improvement
Savings
6% (6.36 mpg) (2.7 km/L)
5% (6.3 mpg) (2.68 km/L)
4% (6.24 mpg) (2.65 km/L)
3% (6.18 mpg) (2.63 km/L)
2% (6.12 mpg) (2.6 km/L)
1% (6.06 mpg) (2.58 km/L)
$5,094/unit/yr.
$4,286/unit/yr.
$3,462/unit/yr.
$2,621/unit/yr.
$1,765/unit/yr.
$ 891/unit/yr.
Calculated using 6 mpg (2.55 km/L) at $4.50 per gallon ($1.19 per liter).
Annual mileage of 120,000 miles (193,121 km).
Cummins Inc.
Box 3005
Columbus, IN 47202-3005
U.S.A.
Phone: 1-800-DIESELS™ (1-800-343-7357)
Fax: 1-800-232-6393
Internet: cumminsengines.com
Twitter.com/CumminsEngines
YouTube.com/CumminsEngines
Bulletin 4971341 Printed in U.S.A. Rev. 7/12
©2012 Cummins Inc.