Yep, they did for a concept car for the VW sponsored Worthersee festival in 2007. And it’s no regular FWD GTI with W12 either.
The Bentley Continental’s W12 didn’t fit under the hood and the front section of the chassis would need to be stretched to accommodate the engine.
Instead of doing that, Volkswagen put the W12 behind the front seats, and made it drive the rear wheels.
The Mark V Golf GTI was widened by 160mm (6.3-in) wider body, lowered by 75mm (3-in) and it has 9-in wide front wheels and 12-in wide rear wheels.
The 6L twin-turbo W12 had 478kW (641hp). The insane Golf W12 had a 0-60mph time of around 3.5s, and a top speed of 323km/h (201mph).