When a man is driving his car and leans his seat back to approx. 180 degrees; lying on his back (naked) and keeping his foot pressured on the gas pedal. His wife, or partner unbuckles herself from the passenger seat, gets naked, hops into the drivers seat and mounts her partners cock with her back to his face. She steers, and honks the horn while riding him (and shifting if in a standard). As he is about to blow it, she shifts into neutral, and he revs the engine. This provides pleasure for both the male and the female, and provides a safe way to get a bone in when you are in a hurry. This is also a great way to pass time on long road trips, for example on a cross country excursion when you are treking through the corn fields of the Mid-West, and you have been driving for days on end-- just roll down all the windows, crank some tunes, and take the Go-Kart for a spin. Generally this works best in a sedan and is an excellent replacement to the road-head. This can also be called a 'submarine' if the women sticks her head out of the sun-roof for visibility.
"Yo Billy, I saw you and Trisha go-karting down West Street last night."
"Honey, we have 110 miles left until Iowa. Let's take the go-kart for a quick spin."
"Sue and I have been working on our submarine for weeks now, and we're pretty confident we can beat Eric and Claire's go-kart on the quarter-mile this weekend.