What Exactly is a Jet Car Boat ? A jet car boat is a water-only vehicle designed to look like a road-going supercar. Built on a fiberglass or composite hull and powered by high-output jet propulsion systems—often sourced from Yamaha or Sea-Doo engines—these machines blend the visceral aesthetics of a Lamborghini or McLaren with the hydroplaning agility of a jet ski. Unlike amphibious vehicles (which drive on land and float or cruise on water), jet car boats do not function on land.