Autocar has taken the most hardcore version M3, the 2011 BMW M3 GTS at Millbrook’s Hill Route proving ground to see if it is faster than a 2010 Porsche 911 GT3.
Here’s what both these cars are capable of : the 2011 BMW M3 GTS produces 444 bhp and 325 lb-ft of torque from its 4.4-litre V8, and thanks to its 7-speed M DCT transmission, the Bavarian coupe can rocket from nought to 62 mph in 4.4 seconds and also reach a top speed of 190 mph.
The 2010 Porsche 911 GT3 extracts its power from a 3.6-litre flat 6-cylinder boxer unit rated at 435 bhp and 317 lb-ft of torque which sprints the wheels via a 6-speed manual gearbox. The GT3 does nought to 60 mph in 4.0 seconds and reaches a maximum speed of 194 mph. 
Both the M3 GTS and the GT3 are rear wheel drive cars, but while the BMW is slightly more powerful, the Porsche has a little more traction due to the fact that the engine is placed at the back. Also the GT3 weights less than the M3 GTS, and as you’ll watch the video you’ll see that the gap between the BMW (who starts behind) and the Porsche becomes bigger.
Conclusion : The 2010 Porsche 911 GT3 remains the benchmark in this class.
 
Video: 2010 Porsche 911 GT3 vs 2011 BMW M3 GTS

Source: Autocar via YouTube