How To Increase Your Gas Mileage

Anatoray

It is, because rather than coasting on downhills it's breaking to keep at speed and drops your RPMs. Cruise control isn't abut efficiency, it's about being lazy and not having to control your speed yourself on long trips.

frost

Fuel efficiency may not have been the original purpose for creating cruise control, but it cannot be denied that using cruise control does indeed help gas mileage.

Edmunds did a test on this, and on average you can increase your mileage by 7%, but it can go up as much as 14%.

Other important notes from their testing, if you're going to idle more than a minute, turn the car off. This can save up to 19%.

Avoiding aggressive driving can save up to 31% (I know, I know, just sayin).

Driving lower speeds on long trips can save up to 14% (again, I know).

Things that didn't matter as much as they expected:
A/C On, Windows Up vs. A/C Off, Windows Down.
Tire pressure. (Which I'm pretty surprised to hear).