How Long Should You Let Your Car Warm Up Before Driving
You can stop warming up your car just because you're worried about your engine. Experts say you only need to let your car run for 30 seconds before taking off, if your car has a fuel injection system, and it almost certainly does.
Warming up your car is one of the biggest winter myths according to this Washington Post article. The story cites a survey which shows many Americans idle their car for over 5 minutes before taking off which doesn't really do anything other than waste gas.
Idling your car to get the heat going and warm up the interior is a completely different thing. Most Minnesotans are OK with wasting a little gas to create a more comfortable driving environment. But in Rochester it's actually illegal to do so. You can actually get a ticket for leaving your keys in a running vehicle on a street or public parking lot unattended. You can read more about that law here.