THE BEST WAY TO WARM UP A CAR IN THE WINTER IS TO NOT WARM IT UP COMPLETELY.
Let me qualify that.
When you first start a car in very cold weather, the fluids that lubricate the engine will be thick and not circulate properly. This means that the engine will not be getting a good flow of lubrication right away so is best to not over rev the engine at this time, but it is okay to drive at a normal rate of speed.
Do not exceed 60kph until you have been driving for at least 5 minutes.
This is not usually a hardship, because most people who have to commute on a freeway will often have to drive on city streets for a few minutes to get to the freeway. By that time the car engine is likely warm enough to take the increased speeds.
If you have been told that you have to warm up a car for at least 15 minutes before driving, this is wrong.
It is very wasteful of fuel, and cars have not needed this kind of babying for over 30 years now.
If it has snowed, then it would make some sense to start the car and let it run while you brush off the snow, or scrape ice off the windows.