Fuel consumption question

[grandpajoe]

I am in dispute with my son re cruise control.
If I drive with cruise control on at a steady 70 is it more economical than with it off and trying to keep a steady 70 "manually" ???
Chris

[Count-A-Strong]

I've always found it slightly less economical with cruise control on, probably because the system tends to let the speed creep up downhill and when you crest a hill. I also don't think that the accelertor is ever fully off with cruise control on (probably depends on the sophisticatio of the car / system) also the actual equipment used to operate the system would put a very small extra 'load' on the engine.

[DTCwordfan]

agree with Count. Less economic - just as automatics are usually less economic than their standard-shift (gear) counterparts.

[AlBags]

Thirded.

[grandpajoe]

Thank you. Looks like I was wrong!!

On motorways , without it, I always ease off the accelerator after cresting a rise. I can feel the economy as I do so.

[Count-A-Strong]

You can feel the economy. Wow.

[DTCwordfan]

He's probably driving a Churchill tank or Foden truck...and anybody with those would feel the economy....

[grandpajoe]

Ah a couple of Fosters takers???
After posting two sensible answers to a straight forward question they both feel the need to take the Fosters!!
Oh well, thanks anyway