I'd expect less than half. The drag of a pair of jet skis is going to be significantly more than the X itself. Perfect use for me though. I drive 500 miles then

I'd expect less than half. The drag of a pair of jet skis is going to be significantly more than the X itself. Perfect use for me though. I drive 500 miles then need to put a boat in the water. My available high efficiency cars can't do the last two miles with a boat, so sometimes I have to drive a full sized pickup truck instead.