G'Day Jas,
Great question and I'd love to know what the painting trade would have to say on that, but from my experience...
My old man's be washing his cars in kero since I can remember. It always cleaned the paintwork really well and leaves a nice water beading finish. It's never damaged the paint, but if there's any chips or bare metal it seemed to accelerate any rust! This next generation doesn't do that anymore!, but spot treatment is fine. That's why it's best to make sure you give it a good wash.