I have an entry for the smallest car ever towing boats (although not a catamaran):

Back in the '70's, a friend of ours, Jim Hirtreiter, had one of the original Hondas that came to this country. It was about the size of a rollerskate (well, maybe 9 feet long). Jim and Rick White towed two Lasers behind that thing from Akron, Ohio to Wichita, Kansas to sail in the Laser Nationals.

Rick says it was probably pretty funny seeing them get in and out of the car, because Jim is 6'4" and Rick was 6'2". Sort of like one of those little cars at the circus where a bunch of clowns climb out of it.

ALSO, back in the early 1980's we had a Volkswagen diesel pickup truck with a cap on it for going to regattas (sleeping in the back). That got 60 mpg without a tow, and dropped down to 40 mpg towing a Hobie 18. Only problem was we couldn't get it into 4th gear when towing. <img src="http://www.catsailor.com/forums/images/graemlins/tongue.gif" alt="" />