Here is a source, with pics,
http://www.nextag.com/blue-flame-heater/shop-html
the smallest one will roast you in quick order, the one in our 35' bus is 10,000BTU, measures about 12" wide, 18" tall and sticks into the room about 6.5". Personally I would not put one (or any supplemental heater) into my Toyota. I took one out after we bought it.
On a really cold morning, we light the oven with the door open, I am sure some will scream "its not safe to do that", but if you think about it, you would cook a roast in the oven, why not use it for 1/2 hr to heat the space. Remember you must have a source of fresh air, and a propane sniffer/alarm is a good idea. We always turn off all heaters before we bed down. Hope this helps, Tony.