BMW M5 prototype with Volkswagen W10 engine heads to auction

A unique prototype BMW M5 E39, featuring a rare Volkswagen W10 engine, is set to be auctioned by Broad Arrow Auctions at the Zoute Concours in Knokke-Heist, Belgium, on October 9, 2026. The vehicle is estimated to sell for between €250,000 and €350,000 (approximately $285,000 to $400,000).

The car was an off-the-books engineering project ordered in 1999 by then-Volkswagen chairman Ferdinand Piëch. Seeking a high-performance engine to compete with BMW, Piëch’s engineers installed an experimental, naturally aspirated 5.0-liter, all-aluminum W10 engine into an E39 M5 chassis. Only three such W10 engines were ever produced, making this the only road-registered car to carry the powerplant.

The W10 engine produces between 473 and 480 hp, outperforming the standard S62 V8 found in production M5 models. While the exterior and interior in Carbon Black Metallic remain largely similar to a standard M5, the vehicle features specialized modifications, including a standalone ECU, a Stack racing dashboard, and the deactivation of anti-lock brakes and traction control. The car is currently road-registered in Slovakia.