I must be the only one here who doesn't use a Coleman. I have a Black and Decker cooler that I got at Target last year. It's still working quite well (although I did have to replace the 12VDC plug because the one it came with wouldn't make good contact in a socket) and doesn't take up the space that the Coleman unit does...
However, I don't have the space for a truck fridge because of my APU's inverter... being placed under the desk in my Century where the fridge would go. But hopefully I'll be getting a T600 soon.