Three is all that will fit in my car. I bring all sorts of support stuff, though. Field box, starter battery pack, chargers, tool box, parts box, prop box, all sorts of stuff.

I am sort of like Opjose.. two "large" and one "small", usually an electric. If I can squeeze in another, it's usually another electric.

I have a Volvo V70 wagon. When I bought it, I had a plane with me to see if it would fit ok in the back. The sales person was sort of curious, but concerned that the car would "pass the test"...

CGr.