I drive a small automatic car. For the most part, it struggles a bit with steep uphills, and picks up speed when going downhill. That’s to be expected.
But then I noticed some downhills actually slow it down. I’ve noticed during a two-hour motorway trip I often do to visit family, there are some specific downhills, not all, just some, where my car always slows down and I have no idea why.
Ideas?
How steep of a downhill and how fast are you going? Gravity will pull depending on the angle of the hill, wind resistance increases with the square of your speed. There will always be a speed where the force pulling you down/forwards will be the same as the force slowing you down due to wind resistance. If you go slower, your car will speed up towards that speed, if you are already faster, it will naturally slow down with no input from the engine or your brakes.
Well, it’s a 110km limit zone for the most part, I’m usually sitting somewhat under the limit but typically above 100. I don’t know how steep these slopes are. Maybe I’m under/overestimating them as a consequence of driving, slopes become obvious on foot. They don’t appear to be particularly steeper that others where my car doesn’t do this. They are certainly not very steep though, because there are a few of those and I gain and lose a lot of momentum on them.