What's the most awesome motorcycle-powered car?

Motorcycle engines may not have been engineered for the demands of a four wheeler, but that's never squelched their employment in some pretty sweet car-like shenanigans — particularly on the racetracks of the world. What's the most awesome motorcycle-powered car?

Had it been built as designed, the Honda GRX concept would likely have been the true spiritual successor to the much-loved CRX. Created for the 2006 Michelin Challenge Design competition and shown at the Detroit auto show that year, the compact GRX was exceptionally light, and so its Honda Goldwing-derived 1,500cc six-cylinder, horizontally opposed engine was a viable powertrain.

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