0MattM60 3 years ago ReplyUpvoteI have made one of this type of heater that fits into your car cup holder and plugs into your power acc. port. It gets up to 1000 degrees f in a matter of 30 seconds. You can use it as a stand alone heater or to heat the car up in half the time. The trick is to calculate the watts, amps and current. My heater is a approx. 100 watt and pulls 7.5 to 8 amps. and puts out 1000 degrees. This is a radiant heater with no fan and heats up the objects in the car and not the whole car. It took me a while to figure out how not to melt my cup holder but is now very safe. I have been using the heater for three years now with no problems because there are no moving parts to go bad. It costs about $50.00 to make.