I drive a PT Cruiser (no laughing) and that motor uses a choking mechanism to start the cold engine (wait...do all cars use choking? i dunno...). but anyway, if i start driving on a cold engine with that rich air/fuel mixture, the engine is peppier (read: more fun) for a few minutes, but i got the 4-speed and it can't keep up with the engine's peppy revs. can't be good for my tranny. so i let it warm up to fool operating temp.