A full bolt on GTR with a tune is a very potent weapon. However, a roll on race between the two cars on the highway assuming similar power should favor the M3. Why? Because it is rear wheel drive, revs higher, and lighter. A run from a stop favors the GTR with its all wheel drive traction and torque advantage. As both cars have a dual clutch transmission that particular area is even.
The M3 pulls surprisingly quickly but it also looks to get a jump on the 'two' count. Regardless, it continues its pull. It would be great to see a rematch between these two cars with the GTR on a race gas map.