Now that the automotive industry is several decades into the era of high-performance SUVs, the first BMW X5 has matured especially well. Even so, when enthusiasts think of classic BMW models from the 2000s, they are more likely to recall performance legends such as the “Clownshoe” Z3 or the E60 M5 with its screaming V-10. Ronnie Fieg, founder of lifestyle brand Kith and a frequent BMW collaboration partner, clearly values both the X5 and its more performance-focused relatives; that is why he had BMW fit an S85 V-10 and a manual gearbox into an E53-generation X5.

Although the E39 M5’s S62 V-8 is actually the period-correct engine for the E53 X5, Fieg’s latest collaboration instead matches the SUV with what could well be the wildest engine ever fitted to any series-production saloon. It is also paired with a six-speed manual transmission — the obvious choice for any enthusiast considering an S85-powered car — and Fieg says that the manual gearbox sends power directly to the vehicle’s original all-wheel-drive system.

As extreme as this particular build may be, it is still far from the most unusual thing BMW has ever created using an E53 X5 and an engine already in its portfolio. That distinction belongs to the X5 Le Mans, an X5 powered by the P75 V-12 from the Le Mans-winning V12 LMR. BMW built that vehicle back in 2000, when both the E53 and the V12 LMR were still new, and it too used a six-speed manual transmission.

The newer of these two extraordinary X5 engine-swap projects is due to make its debut at BMW’s Pebble Beach activation this weekend as part of a new “Kith for BMW” partnership. Fieg also mentions that a Kith-branded 2027 BMW X5 will be displayed at the same event, along with an E9 3.0 CSL and an E24 6-Series finished in Inka Orange.