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April 14, 2025 – German exotic car manufacturer Ruf has taken a major step beyond its Porsche roots with the reveal of the B8 Erprober, a prototype packing a brand-new 4.8-liter twin-turbo flat-eight engine that delivers over 1,000 horsepower. The machine debuted at the 2025 Goodwood Festival of Speed in England, where American stunt driver and three-time Rallycross champion Tanner Foust put it through its paces on the famous hill climb. The B8 Erprober ran twice daily from July 10 through July 12, marking the first public demonstration of Ruf’s most ambitious engine project to date.
The B8 – which stands for Boxer 8 – is a horizontally opposed flat-eight, a layout familiar from Porsche and Subaru but rarely seen in modern high-performance cars. The 4.8-liter unit is force-fed by twin turbochargers, and all its power is sent to the rear wheels through a six-speed manual transmission. That’s right: a manual. In an era of paddle-shifters and dual-clutch automatics, Ruf is betting on the old-school three-pedal setup to deliver the driving experience enthusiasts crave. The prototype itself is based on a heavily modified CTR3, stretched 100 millimeters to accommodate the extra two cylinders compared to the standard flat-six.
Ruf has been building its own cars since the early 1980s, when it gained the right to assign its own VINs. While many of its models visually echo Porsche designs, the company now produces carbon monocoque chassis for its latest creations – including the retro off-road Rodeo, which makes even the Porsche 911 Dakar look tame. The CTR3, first introduced in 2007, was Ruf’s first bespoke vehicle. It uses a Porsche 911 front clip but is mid-engined, lower, and rides on a longer wheelbase, with a chassis built by Canada’s Multimatic (the same company behind the Ford GT Mk IV). The only shared parts with Porsche are the wipers and glass.
The B8 Erprober represents a new chapter. Ruf has stated that the engine itself will not go into production in its current form. Instead, it serves as “a dedicated testbed for technologies that will shape a future RUF model.” This suggests that the lessons learned from the B8’s extreme power, thermal management, and packaging could lead to a production car – perhaps as early as the 2026 Goodwood Festival. The company has not disclosed any timeline, but the prototype’s full carbon-fiber body and custom livery hint at a serious engineering push.
The livery was designed by Alosia Ruf, a third-generation family member and artist who handles public relations and marketing for the company. The yellow hue matches the Blossom Yellow of the iconic Ruf CTR Yellowbird, linking the prototype to the brand’s heritage. Sponsor Optima Batteries – known for some of the best warranties in the car battery market – also had a hand in the design, featuring an eight-cylinder graphic on the engine cover and its logo on the rear spoiler.
Why the flat-eight matters
Flat-eight engines are rare. Porsche famously used air-cooled flat-eights in the 917 and 908 race cars, but they never made it into road cars. Subaru considered a flat-eight for the SVX but never built it. Ruf’s B8 revives the concept with modern turbocharging and direct injection, offering a compact, low-center-of-gravity package that can theoretically rev higher and handle more boost than a V8. The 1,000 hp figure places it alongside modern hypercar engines, but the manual transmission is a deliberate throwback – a statement that raw driver engagement matters more than lap times.
What’s next for Ruf?
The B8 Erprober is not a one-off. Ruf has confirmed that the testbed program will continue, with the goal of refining the engine for a future production model. The company’s recent shift toward in-house platforms (the Rodeo, the new CTR) suggests that the next Ruf hypercar could be entirely its own, not just a modified Porsche. With the B8 engine, Ruf is positioning itself as a true independent manufacturer, capable of developing its own powertrains from scratch.
Automotive analyst Michael Schmidt, who has followed Ruf for 20 years, notes: “Ruf has always been more than a tuner. The B8 proves they
