Cooling systems and pipe materials
1) Cooling system. Its almost a must. Fans, radiators, inter-coolers, pipes etc. Nothing to advanced, just being able to select: small or big radiator/ IC, with fan or not. (the fan should rotate in engine designer, I love the rotating parts

2) Pipe material. I would love to be able to choose between ordinary rubber and silicon pipes to the cooling system. (yes I want blue/red silicon pipes) Silicon = costs a bit but better lifespan.
Keep your good work up! I will try spread the word about this game
