There is a belief among a lot of people that you should start your car and leave it on for 5 minutes before moving it in the morning. Is this practice good for the car in any significant way, or it is just a myth?
Once upon a time on old car engines this was required, and piston engined aircraft warm up because they stress their engines to the maximum as the first thing they do. But this is no longer necessary for modern cars. The recommended warmup time vary between 15 seconds and three minutes.
Contrary to popular belief, excessive idling is not an effective way to warm up your vehicle, even in cold weather. The best way to warm it up is to drive it. In fact, with today's computer-controlled engines, even on cold winter days, usually no more than two to three minutes of idling is enough warm-up time needed for the average vehicle before starting to drive
"get into your car, start the engine, and while putting on your seat belt, getting comfortable, checking your mirrors and turning on your radio, 30-45 seconds have passed, so put it in gear and off you go"
Toyota Canada, [...] representative said it’s not necessary to warm your vehicle, nor will doing so cause any harm. The rep adds that there are pros and cons: the motor and oil will warm, and the coolant will flow – but idling for long is harder on the environment.
The Canadian Office of Energy Efficiency agrees that the best way to warm up your engine is to drive it. Even if the outside temperature is -20°C, they recommend that you idle the engine for only 15-30 seconds before you pull out onto the road.