Haha, I never tried to haul any of mine in a car. I did take a Honda XR650R apart, put it in the backseat and trunk of an old Ford Taurus and drove it to my friend's place in Virginia from NY and we reassembled it and rode it that day. But no, around this area they're too busy not paying attention to anything else so they're just running their machines up on the shore and getting thrown off, crashing into each other or into the side of boats, or dumping themselves and their passengers off when they're going too fast for the conditions of the lake.
Here's a picture of another way to haul a machine.......it's not 100% a water vehicle, but rather an amphibious ATV. A guy named Amphiman1 brought his 6 wheel amphibious ATV home like this.