I just got a heater for my other car. I wanted something that would warm up the car ASAP so I didn't have to wait and could use it on a whim or unplanned trip. I don't leave it plugged in all the time because they're huge energy hogs. Anyawy, I ended up getting a katz 1000W circulating heater. I figure even 30 minutes with it on should give the coolant a good boost in temperature. To go along with it, I got a remote control switch for it. So, I get up in the morning, turn on the block heater, get ready and go out to a warm car.