The GT3 4.0 boasts the biggest hp/liter figure around - 125 hp/liter (92 kW) from a naturally-aspirated 4.0 liter unit.

Porsche has made it official - this is the 911 GT3 RS 4.0.

Details are pretty much as we reported them yesterday.

It will be a limited edition of just 600 units and power will come from a naturally-aspirated 4.0 liter engine sourced from the race-bred 911 GT3 RSR. The 4.0 liter is the biggest engine ever offered in a Porsche which translates into a hp/liter figure around - 125 hp/liter (92 kW) and 368 hp/tonne.

That makes for a total output of 500 PS (368 kW / 493 hp) but now we have a torque rating from Porsche of 460 Nm (339 lb-ft). Transmission will be a six-speed sport gearbox.

Weighing just 1,360 kilograms (2998 lbs) the car does the 0 to 100 km/h (62 mph) sprint in only 3.9 seconds and the GT3 RS 4.0 rounds the Nürburgring-Nordschleife in 7:27 minutes.

The Porsche 911 GT3 RS 4.0 goes on sale in Germany and UK in July with prices starting at €178,596, VAT and the £128,466 respectively.

See the press release below for full details.