Remote starting a car and letting it sit is a good way to have it stolen. It is also tough on the motor. The best way to warm up a car in cold weather is to start the motor, and start moving after about a minnute. this allows fluids to move around and it will warm up faster than sitting at idle. Years back when I worked in a repair shop, I always had a bunch of cars come in with the exhaust systems full of ice from remote starters. People would remote start cars, run them for a bit, then shut them off. That would let the water vapors build up in the exhaust and freeze. If they would have driven them enough to blow out the exhaust, it would not have been a problem.
It doesn't take that long to warm up a smart. the interior is small enough, and the motor is small enough to just get in and drive.