As a testament to the incredible natural poise the GT3 RS possesses, this footage shows how well it fares against an already-potent M4 with a slew of modifications and a talented driver. Some might regard this as an unfair match, a track car against a mildly-tuned grand tourer, but it's actually a closely run battle between two focused machines with slightly different repertoires.
Clearly, the BMW, tuned by French outfit , is the slower of the two from the get-go. However, add a set of 295-section Pirelli Trofeo R tires (they appear to be a bit stickier than the Porsche's Pilot Sport Cup 2 tires) and KW Clubsport V3 coilovers, and the overall grip of the Bimmer is roughly on-par with the Porsche—at least in the some sections. In slower bends, like Adenauer Forst (2:37). the BMW shows a subtle amount of oversteer. It's still quick, but it cannot compete with the rear-engine traction of the RS in pursuit.
Another area where the BMW is lacking is the braking zone. Crucially, the BMW tips the scales at 3,600 pounds, but AP Racing Pro 5000 R brakes and Pagid RSL1 pads help the car decelerate repeatedly and confidently. Yet, the Porsche's weight distribution and svelte frame give it an advantage in every heavy braking zone.
So, where does the BMW have an advantage? After all, the Nürburgring is made up of tight, technical sections. The answer is in the high-speed portions of the track, where a tuned engine and turbocharged torque help equal the playing field.
The M4 can stretch a small lead once the course straightens, thanks to its aerodynamic additions as well as a whopping 553 lb-ft of torque and 580 horsepower. Not only is it the better dragster from 60-120, but it shows almost as much speed through high-speed sections, like Fuchsröhre (2:10). If ever there was a doubt about the relative skills of the drivers, it's evident from the aforementioned section that they're equally precise and courageous.
In conclusion, it shows that on stickier tires and with more power, the M4 is as potent on the 'Ring as the Porsche. I'll refrain from a diplomatic sendoff: points for power go to the BMW, but for low and mid-speed brilliance, the RS is the clear winner, and not much slower once the course straightens.
It's safe to say the King hasn't yet relinquished the throne.