i just go...warms up faster that way...besides your temp gauge only measures water temp. for oil temps to reach the right point would take too damn long since when your idling your oil doesnt circulate very fast
Let the car run idle for a couple minutes. If it is extremely cold (20 and below) then let it run for a couple more. Then drive. You don't want to let it idle until operating temp has been reached, however you want to let it run long enough to circulate oil AND transmission fluid (for automatics) and build a little heat inside the engine.
:driving From what I have read in magazines such as Car and Driver and mechanic's replies, cars are designed to warm up while driving. It's been some time since I read this and I'm not sure what is in the design.
Ive heard both sides of the Argument. I think on American cars its a good idea to let them warm up a little since the ones ive owned sound very rough if you just start them and go on 20 degree or less weather. The bimmer so far has not cared either way, and I would imagine by this point these engines are designed not to need to idle, especially with environmental standards the way they are these days.