I can attest that a 1983 Cadillac el dorado 2 door will not carry 14 sheets of 1/2 drywall strapped to the roof without blowing the air ride suspension.

It was at that point I also realized that if it did not hold a 4x8 sheet of plywood in the bed then it was worthless,with the back seats down a 1989 Volvo 740 station wagon will hold 16 sheets of plywood in the back.