Algodoo

Uses a 6-pot spawn engine that relies on ellipse-shaped cams to provide the timing... but with the daftness of gravity to return the pistons.
The result is a thing that works sweet under high load and very low RPM, but shortens its combustion cycles to the point of cutting out as the RPM increases. It also won't work unless it's more or less sitting upright. (Although if your whole vehicle is upside down then your engine running is the least of your concerns).

Sat the engine in my conventional chassis & gearbox, if anything showing that at least in this first-off rendition how comparatively weak it is.

~~~~~
Same 7-Speed gearbox, but now with 2 sets:
Low set on G, High set on T.
Gears toggled on 1 through to 7.
Rightward toggled on F,
Leftward toggled on R.
S for brakes.

There's a course rightward to traverse.