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As winter comes along, I've always thought that revving the car would make it warm up faster, so the heating works better to clear the icy/steamed up windows.

Does revving my car at idle to about 2-3k when cold (less than 5C outside) make it warm up faster?

Does revving higher (like to 4k max) when driving, and driving in a lower gear than usual make it warm up faster? Obviously going to the redline when cold is stupid.

Are there any caveats to doing this?

Note: I meant also to use it for defrosting the car when it is covered in ice, as you can't really drive when you can't see! ;)

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    If it is modern (or old) diesel engine, then idling does not help a lot. Modern diesel engines are very efficient, so it wont warm up while idling. If it is petrol, then you can idle. Of course if load is higher then faster engine heats up. I personally in winter at morning start my car and then i go breakfasting. (vehicle is locked). After that inside is warm and windows not need to clear. – Guntis Oct 10 '15 at 7:31
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The short answer: Yes, you can rev your engine to make it warm up faster.


One big caveat to that answer is that it is highly recommended you don't do that. With modern gasoline vehicles, most manufacturers recommend you start the car and immediately start driving. The reasons for this are many, but a couple of the major points:

  1. The car will warm up faster by driving it than letting it sit in your driveway for several minutes. Most of the moving parts outside the engine will not be warmed up by idling it in the driveway before you drive, they can only warm up by driving.
  2. Your car will be putting off a lot of pollutants for no reason as it just sits there warming up. It's a waste of fuel for little to no benefit except your comfort.

This myth is a carry over from the days of carburetors, which did need some warming up before driving.

My recommendation: Put on a jacket or coat and just start your car and gently drive away; it'll warm up in a few minutes. If it's extremely cold out, let it run for maybe 30 seconds before driving. Don't push it too hard until it has warmed up. If you sit there revving the engine to warm it up faster, you might as well be driving because you are going to be putting extra wear and tear on the vehicle by revving it too high while cold.

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To expand on Poisson's answer given your edit - Yes, you can, but still shouldn't ;) . By the time you've scraped the ice off the side windows the demisters should have done the job with the front and rear screens (or at least loosened the ice enough to make it easy to wipe off), at which point you're good to go...

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Generally speaking, more load equals more heat. Revving the engine in neutral produces slightly more load than idling in neutral. But not by much. Actually driving the car around will heat it up faster.

Keep in mind that cold oil pressure will be a lot higher than warm oil pressure and oil pressure is also proportional to RPM. The oil pump should have a pressure relief valve, but they vary in effectiveness. So you probably shouldn't be bouncing off the rev limiter when your engine is still at -20 degrees.

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