In the past, the common practice was to “gear up and let it idle to warm up my car’s engine.” However, contrary to this former best practice, this strategy does not prolong the life of your engine. In fact, it strips oil away from the engine's cylinders and pistons.
In an internal combustion engine, pistons compress a mixture of air and vaporized fuel within each of the engine’s cylinders. The mixture is then ignited to create a combustion event, like a small, controlled explosion that powers the engine.
But, when your engine is cold, the gasoline is less likely to evaporate and create the correct ratio of air and vaporized fuel for these small explosions. Engines with electronic fuel injection have sensors that compensate for the cold by pumping more gasoline into the mixture. The engine continues to run this way until it heats up to about 40 degrees.
Driving your car is the quickest way to warm up the engine so it switches back to a normal fuel-air ratio. Even though warm air generated by the radiator will flow into the cabin after a few minutes, idling the car does very little to warm up the actual engine. The best thing to do is start the car, take a minute to scrape the ice off your windows, and get on the road.
Of course, hopping into your car and gunning it straightaway will put unnecessary strain on your engine. It does take 5 to 15 minutes for your engine to warm up, so take it nice and easy for the first part of your drive.
So why do people still think they need to let their car warm up?
Back when carbureted engines owned the roads, warming up your car’s engine was a best practice. Carburetors mixed gasoline and air to make vaporized fuel to run an engine, but they didn't have sensors to adjust the gasoline-air ratio when it turned cold. As a result, you had to let older cars warm up before driving or they would stall out. Luckily, it's been about 30 years since carbureted engines were common in cars.