Does Cruise Control Save Fuel or Use More Fuel?

Try it more than a few times.

 

its sort of like whats better a chevy or a ford. answer depends on who you ask

 

IMO Depends a lot on the terrain. Flat land it can driving thru the hills not so much.

 

I think it's to aggressive for the hills. I don't want to crest a hill at 100% throttle when gravity is waiting on the other side. waste of fuel.

 

There has to be a way to tweak that setting.

 

But that's an anecdotal assessment not a scientific one. If you want to know the true answer, you need to do what I said above, try it more than a few times. Run for a month or better yet, two months or three (the more the better) with no cruise control. Then divide miles driven in that time by fuel used. Then drive the same amount of months using cruise control as much as possible. Divide miles driven by fuel used and compare the results. Then you'll have a better answer.

 

one truck, or even a few trucks, is STILL an anecdotal assessment, even if you did it for a few months, or even throughout the life of the engine. to know the true answer, youd need a much more scientific study than one or a few guys observing results in their own trucks. so, yes, all you will get by asking on a forum like this is going to be a subjective answer.

 

For me, its not fuel...its staying out of trouble. But since you are asking about fuel economy, I would say that it would depend on how a truck is set up. Most factory setups have the 'soft cruise' setup. Without soft cruise, going uphill feels like you're about to have one of those Toyota moments where the throttle gets stuck at WOT. If you have the cruise set on 65, it hits 100% of HP until you reach 65. On foot, you wouldnt do 100% once you got near 65. Youre at 64mph and shes still at WOT, and you wonder, "Is she going stop at 65???" So, in a 65 mph truck with soft cruise engaged, I would say that you really shouldnt be able to see much difference.

Now, if you are in a faster truck and about to hit the hills, I would put the throttle down a bit to spool the turbo. See cruise doesnt kick in until you drop several MPH. And the turbo has to spool up and start boosting. You lose alot of momentum waiting on the cruise to kick in. When the turbo kicks in, youre at WOT without momentum. Even if you were running 65 on cruise, its better to put the throttle down a bit, kick up the speed to about 70-72, get the turbo spooled and use the extra momentum to top the hill. Better fuel economy and easier on the engine and driver.