When driving on the highway or freeway, a constant, moderate speed is more efficient and 
economical than constantly accelerating and braking. Usually you can reach your destination just as 
quickly by driving at a moderate, but steady speed. 
The cruise control system can assist in maintaining a uniform driving style. 
Moderate use of extra electrical loads 
Comfort inside the vehicle is nice and important, but it is important to use them in an environmentally 
conscious manner. 
Some devices can increase fuel consumption when activated (examples): 
 x Climate control system (air conditioner): If the climate control system has to produce starkly 
contrasting temperatures, it requires a large amount of energy, which is generated by the engine. The 
temperature in the vehicle should therefore not be extremely different from that of the outside 
temperature. It may be helpful to ventilate the vehicle before driving and then to drive a short distance 
with the windows open. After that, switch on the air conditioner with the windows closed. Keep the 
windows closed when driving at high speeds. Open windows increase fuel consumption. 
 x Switch off seat heating once it has served its purpose. 
 x Switch off the windshield and rear window defroster as soon as the windows are free of fog and 
ice. 
Additional factors that increase fuel consumption (examples): 
 x Malfunctioning engine control. 
 x Driving in the mountains. 
 x Towing a trailer. 
Fuel-efficient driving 
 
Fig. 249 Fuel consumption at 2 different outside air temperatures.