I had an old Series era Landrover as a paddock basher when I was a kid, that had a manual choke. It also had a backup crank handle for starting the engine which I had to use occasionally as I was using starter batteries which had been retired from usage in the family cars, a gearbox with no synchro on first/second, and the foot brake didn’t work. Would recommend, I definitely had fun.

That’s one with big potential but not one to lead off with, best to wait until you’ve ‘invented’ a few obvious game changers and established your philosophic credentials before attempting to introduce basic medical hygiene…

Electricity is a hard ask to even attempt to do in ancient times. Luckily there’s a variety of other simpler things to establish yourself as a genius inventor - strirrups, wheelbarrows, magnetic compasses, the idea of a crank handle, and how to use triangular bracing to make a strong truss would be good options.

Better not let any clean freaks see this - they’ll have a cow!