My car heats up very quickly, indeed, I think the ATX shifts higher to let the car rev more and heat it up faster. Of course, I live in a spot that's never once (at least, I'm pretty sure about this) hit zero faranheit, so I have a natural advantage, but when I get off of work and I'm trying to defrost my body from the freezer I spend hours in, my Mz3 cranks the heat quickly (I'd say 1-2 minutes) enough to make me turn it way down after 30 seconds to warm up the whole interior. btw, do you think that the rear vents steal the air even if it's not warm air, as in if you've got the system set to mix floor and vents? Is this why there's not much air coming out if the system is set low?