Algodoo

Started off as another attempt at making a high-density spawn engine, like my W4 turned out to be to great success.
To get around the thing trying to take off with the high spawned mass, I flipped two of the cylinders over, and consequently had to put in a balancing counterweight to stop the thing shaking so much.
Ended up anyway reducing the densities, which made it run better. It's resulted in this very low rev, super high torque thing that can drive off in 5th.

To demonstrate the inherent engine vibration, the balance phase can be adjusted whilst the thing's running (how I found the sweetspot), or just delete the bright red little circle.

Controls in-scene
Course rightward to traverse