This builder took a Volkswagen Jetta with a VR6 up front (already a good place to start), chopped out the rear seats, put in a roll cage and mounted a W8 engine back there. To make it all work together, he hooked the throttles together, but each powerplant still operated with its own transmission with VR6 using a manual and the W8 having an automatic.
Amazingly, at first glance, this 14-cylinder Volkswagen looks like a mostly stock Jetta. However, the ability to hide out is instantly erased as soon as you hear this thing or take even the quickest glance in the rear. With the two engines shifting completely separately from each other, the result is a wall of glorious automotive sound.
Check out the video to see the guy's handiwork and see what happens when he mashes the throttle to make two VW engines motivate this Jetta on a dirt road.