When driving through hilly terrain, just let your car lose its speed while keeping your right foot still. Don't worry as you'll gain all the speed back later when going downhill.
Adjust your throttle accordingly so that you don't slow down too much. It pays to also gain speed to a sufficient level before hitting the uphill so that you don't need to accelerate mid way.
Do not use cruise control at all. This system will to needlessly accelerate your car when climbing up hill to obsessively keep its set speed.
by BenjaminWKI on February 08 2011
this tip works for 85% of voting Fuelly members.