Originally posted by MJT:
Any thoughts on whether fuel consumption is adversely affected by use of cruise control?.
I don't think that there is really a clear cut answer to this, because it depends on a variety of conditions, most of all terrain. Driving with the cruise control, on the flat plains of Texas and driving with it on in West Virginia, would have completely opposite results for example IMHO.
Supposedly, gas mileage decreases rapidly at speeds above 60 mph. Each 5 mph you drive over 60 mph is like paying an additional $0.15 per gallon for gas
Also stuff like using the A/C, state of engine tune, timing, tire inflation levels, vehicle gross weight, oil type, and accessory use all play a role in MPG.