Are they supercars? Are they sports cars? Well, who really knows, and who really cares about the semantics - they're both hilariously powerful rear-wheel drive coupes, and we want to know which one would win in a good old game of Top Trumps.
The cars
The Mercedes-AMG GT R arrived in a lurid green flurry of extravagantly long bonnet and anti-social V8 savageness, and we love it. It's lairy without being terrifying, precise without being characterless. The Porsche 911 GT2 RS might have a two fewer cylinders, but the evergreen appeal of Porsche's rear-engined sports car is still strong in this bonkers take on the rear-engined icon. We've driven both, and neither is the widow-maker you might be expecting considering the amount of power going to the rear wheels, but here's how they stack up on the figures:
| Mercedes-AMG GT R | Porsche 911 GT2 RS | |
| Price | $157,000 | $293,200 |
| Engine | Biturbocharged 4.0-Liter V8 | Biturbocharged 3.8-Liter H6 |
| Transmission | 7-Speed DCT | 7-Speed DCT |
| Drivetrain | Rear-wheel drive | Rear-wheel drive |
| Power | 577 hp at 6,250rpm | 690 hp at 7,000rpm |
| Torque | 516 lb-ft at 1,900 - 5,500rpm | 553 lb-ft at 2,500-4,500rpm |
| Power to weight | 354 hp per tonne | 447 hp per tonne |
| 0-62mph | 3.6 seconds | 2.8 seconds |
| Top speed | 198 mph (314 kph) | 211 mph (340 kph) |
| CO2 emissions | 259 g/km | 269 g/km |
| Seats | 2 | 2 |
| Length | 4,551 mm | 4,549 mm |
| Width | 2,075mm (inc. mirrors) | 1,978mm (incl. mirrors) |
| Height | 1,284 mm | 1,297 mm |
| Wheelbase | 2,630 mm | 2,453 mm |
| Weight | 3,594 lbs (1,630 kg) | 3,406 lbs (1,545 kg) |
| Fuel tank capacity | 85 liters | 64 liters |
Which one wins?
Well, it's got to go to the Porsche. Truthfully, this is an unfair fight given the Porsche's much higher price and power output, but in spirit and execution there are a lot of similarities between these two hairy-chested rear-wheel drive coupes. In fact, the AMG GT-R held the Nurburgring lap record for rear-wheel drive production cars with a time of 7:10.9 minutes, until the Porsche 911 GT2 RS set an astonishing time of 6:47.3 minutes.
But leaving the numbers game aside for a moment, which one looks best and which one would we want on our driveway? Hmm. It'd probably be green.
Gallery: Mercedes-AMG GT R
Gallery: 2018 Porsche 911 GT2 RS: First Drive