You can install roll cages in some vehicles: not only is it safer, but it improves chassis stiffness and vehicle handling (use [action=parts_selector]).
Operating an engine upside down causes oil starvation. Blue exhaust smoke will occur from oil submerging the cylinders, and the engine bearings could fail.
When cornering with a keyboard, repeatedly tap [action=steer_left] or [action=steer_right] to better control the steering angle and prevent unwanted understeer.