Algodoo

This one works more like a combustion engine, I think.

If you need more power just change the values.

This one has only 1 gear.

Rather to use a reverse gear, it changes ignition timing to go backward like a steam locomotive.

S - starter
W - throttle
N - clutch (toggle)
R - Reverse Engine Rotation (toggle)
X - Release car

no brakes

For some reason, if you reach top speed in neutral or reverse, then press R without releasing the throttle, the engine will go faster.

Feel free to edit