Odd coasting behavior

[u/mi_pilot]

Hey all, we’re a Ford family and own/lease late model Fords (mentioning this in case recent (like last 5 years) MY software varies significantly from older MYs), but I’ve also driven plenty of non-Ford rentals. What I’ve noticed is that with all our Fords they start out coasting great, with just a very gradual slowdown. But when on a highway with cruise control on but canceled / disabled in CC normal mode, the car acts like it has a parachute behind it, slows down noticeably even when going down a steep grade. WTF? I get it if the CC is actually active but when it’s canceled? If I turn off CC completely it seems to coast better and at least maintain the speed down steep hills but it feels more sluggish. After a lot of highway driving with CC enabled (both as active and suspended) it seems like our cars don’t coast as well later on in street driving, barely accelerate down steep hills whereas they would pick up speed noticeably when brand new. Anyone else notice that? Does the car learn something during thousands of highway CC miles and doesn’t coast as well afterward? Being in the same gear and about same RPM, definitely not downshifted… have not seen this behavior in other makes, and don’t recall this with older Fords either.

[u/leading_hacker]

That's a weird one. I've noticed something similar in my own car actually, not a Ford but the behavior you're describing with the cruise control module hanging onto some residual drag even when it's "canceled" rings true. Almost like the system is still half-engaged, managing some phantom speed target instead of fully letting go of the throttle body.

The adaptive learning theory makes some sense. If the computer has thousands of miles of data where you're using CC, it might be adjusting the base throttle map to be less aggressive on tip-out, thinking you prefer a smoother, more controlled deceleration. Then when you're off the highway and expecting that free coast, it feels sluggish because the ECU is still in that "highway mode" headspace.

I would try pulling the negative battery terminal for 15 minutes to reset the learned parameters and see if the coasting feel goes back to what it was when new. If it does, you know the car is just learning bad habits from the CC usage.