Hello.
When I was boring I did some stupidity and found out this. When I pushed car on bump and rear wheels didnt have any contact with ground and they were rotary I turned off engine. Wheel rotary animation stoped also it showed 0 kmh. In some moments it showed speed and rotary animation but then it stoped. When I started engine, animation started and speed started to show. Also i found out that wheels doesnt make any sound rotating at 270km/h but it is just a feature. Sorry for gramar and if this bug was known.

That's intentional. Cars with disabled engine are removed from the physics calculations for performance optimization. Not "realistic," but it makes sense in the game environment.