Originally Posted by rvsprinterguy
Interesting question. I don't think any vehicle with cruise control I've owned did anything to reduce speed downhill other than "take its foot off the gas". My Sprinter certainly downshifts when necessary to maintain speed going uphill, but downhill braking is the driver's job. In the Sprinter, I've not found downshifting manually to be much use in the compression braking department. I'm hyper vigilant watching downhill speed because the vehicle is really very heavy.
When I'm driving on cruise control in my Sprinter and car for that matter, both of them will downshift automatically when they pick up speed on a descent.
The only time I manually do it is if I'm not using cruise control or had to slow down on an emergency basis for control. Yes, it does add to braking....but, I don't over do it.