The biggest hurdle in developing the GT2 RS? "First of all, it was how much power we can get," Rohrl told CarAdvice at this year's Goodwood Festival of Speed.
"That was maybe the biggest challenge. We were trying some different things, and finally, it was of course because Ferrari has 680hp we have to try to get 700hp. It was not so easy to get to 700hp."
The 700hp (515kW) figure, is a huge step for the 911, but even more so when you consider the GT2 RS remains rear-wheel drive. It does however for the first time, get rear-wheel steering.
"You know, I think the electronics are always getting better and better because I would say, five years ago, it would be no way to have 700hp for rear-wheel drive," Rohrl told CarAdvice. "But today it is amazing how good it works."
Is the rear-wheel steering integral, then, in harnessing such a stratospheric power figure?
"Yeah, for sure the rear-wheel-steering is part of using that power safely," Rohrl said. "The biggest advantage of four-wheel-steering is if you make a quick lane change. It's not really the handling.
"Of course, in a tight corner, it helps you that the car is turning in better. The biggest advantage is that quick lane change, though. It is much safer, much easier to drive."
While the GT2 RS is an undoubted thoroughbred with track ability, it is first and foremost a road car. Both Rohrl and Mark Webber were keen to emphasise that point at launch.
"Of course it is still... I always say it like this - a car needs so much power that it is only enough if in the morning when want to start it if you are already afraid," Rohrl said laughing. "It is still not this number of horsepower though that the GT2 RS makes. You enjoy it everyday and it is a new challenge and new fun to drive this car."
Webber agrees. "This is very much a capable road car," he said. "I always like my cars to have navigation and air conditioning, things I can use to make it enjoyable on the road. And while this car is ballistic, incredibly fast, there's no doubt you can drive it on the road."
For his part, and with a long and storied career in motorsport, Rohrl is as amazed as we are that modern cars can harness so much power, so safely.
"Absolutely, I always say before, twenty years ago for example, everybody says if I have a lot of power it is easy to win," Rohrl said. "But it wasn't like this though. I know many drivers who were faster with a smaller amount of power. Because it was only up to you, to handle and use this power. Today it is all about the technicality of the car."