Car appreciation... the aesthetics, the engineering, etc

Is it using a sequential(?) bike shifter? I guess it's light enough to roll backwards if you ever needed to.

Yep, it uses the standard bike gearbox, so a 6 speed sequential with no synchros, just a dog shift. You basically just replace the output sprocket with a propshaft adaptor, turn the engine round 90 degrees, and bolt a propshaft to it. The gear shift was originally a fore-aft stick shift, but I converted it to a mechanical paddle shift behind the steering wheel - right hand for down, left hand for up.

The reverse was a biomechanical voice-operated reversing unit. In other words, if we needed to go backwards, @Cycliste would hop out and push the car backwards. Generally only necessary in car parks - the rest of the time a bit of lock, lots of revs and dumping the clutch would soon have you pointing in the opposite direction. It is fairly light - 420kg with fluids.