I have driven the R today, shared my GT4 with my friend and exchanged cars a few times. Drove them on mountain roads, speeds lower than 150 km/h, bumpy and pretty curvy. Temperature around 8-12 degrees. Both cars with Michelin Sport Cup 2. Please bear in mind this context whilst reading my impressions. On high speed roads the conclusions could be very different. We drove around 300 Kms.
It is unbelievable how different both cars feel, both great Porsches as they are. Both absorb the road holes and surface changes without changing the trajectory. The GT4 is more precise, inspires more confidence from the beginning and it is easier to go fast. The R, a pure 911, has a lighter steering and the inside engine note is dominated by the intake. I had to hold the R tighter to keep it in the lane (again, mountain road, bumpy and 120-130 km/h). The GT4, on the other side, is pure exhaust noise. The sound symposer makes a big difference, it seems. Manual box in the GT4 feels better: more precise and metallic. Clutch pedal is softer in the R, a surprise.
On the other hand, the R engine is awesome. The single mass flywheel is always present, like in my old GT3 RS. At mountain road speeds, both cars feel as fast. But the R simply flies if you drive it above 6000 rpm. I wish my GT4 had this engine! Interestingly, the rev match function is very different in the two cars: the GT4 is more aggressive on downshifts, with a clear bang. The R rev matches on upshifts and on downshifts is smoother. Seems the character is clearly marked: a Porsche GT car vs. an awesome road car. Noise insulation in the R is minimal, you feel every stone hitting the wheels arches.
The owner of the R came more impressed with my car than me with his. Maybe my expectations of the R were high enough, but truth to be told: I cannot understand how Porsche priced the GT4 so low. It is such an awesome car that it stands a face to face with the R on this driving conditions. I prefer the R, no doubt. I am a 911 guy, but I cannot stop smiling every time I step out of the GT4.
The R is such a great car, the manual 991.2 GT3 will be a blast!
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2016 Cayman GT4 - 1992 964 Carrera 2 - 2016 Macan S Diesel - 2013 Mini Cooper S