I have read in an article that when the car is in gear instead of being in neutral while driving downhill, the pistons in the engine are being "rotated" by the rotational speed of the wheels.
When the car is in - for example - 3th gear going down a steep hill, the RPM was about 3000. When I shift up to 4th gear, the RPM drops to about 2000.

My question is, why does the RPM drop if the wheels are rotating at the same angular speed?


As you say you change gear from 3rd to 4th, this means you have changed the gear ratio between the engine and the wheels causing a different engine rpm.

  • To the phantom downvoter, I seem to add points faster than you remove them.... :)
    – Solar Mike
    Jun 17 '19 at 16:56

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