He has driven this track thousands of times since coming here more than 30 years ago and this all-action episode is a practical reward for my coming to Germany to tell him he’s just won Autocar’s highest accolade, the 2015 Issigonis Trophy, which goes to car creators we especially admire, not only for the quality of their work but also for their way of doing it.
For all his familiarity with the circuit, you can tell in an instant that Hatz continues to have an abiding love for the place.
He revels in Porsche’s history and aura and his chance to contribute to both, in spite of a career that has taken him to BMW, Opel, Fiat-Ferrari, Audi and Volkswagen – and into sundry winning Formula 1 teams.
He considers himself a Porsche man and always will, having done his first laps here as a postgraduate engineering student in 1982.
“Everything is so concentrated here,” he says, “and that makes for a very special atmosphere.
"Our workshop people are so important and so knowledgeable, and we all have the same determination to reach our goals. It leads to a unique kind of team spirit.”
The post of director of R&D at Porsche is one of those roles in the car business that carry far more responsibility than the mere words imply.
Far from being some back-room researcher, Porsche’s R&D boss is fully exposed in the front line of management and car creation.
You lead the teams that devise the company’s racing and road car strategies, and it’s your responsibility to deliver wins and new models every bit as good as you’ve promised, preferably better.
You hire, deploy and inspire the company’s most creative people – and you get plenty of freedom and glory yourself if things go well.
But there’s a boardroom full of founding family members and money men looking down in case you don’t.
Oh, and somewhere along the road, you’d better direct your thoughts towards the R&D in your title.
Depending on how you view it, the future for high-performance premium cars, and especially sports cars, can look rather problematic.
Hatz acknowledges that computers do a lot to build new cars but insists that Weissach’s value is just as great as it ever was.
“I need to keep testing our cars,” he explains, “and I probably spend 25% of my time doing that.
"I look for quality – not just quality you can see, but quality in the way a car goes and drives.
"Here at the track, I can drive one of our prototypes through the very first corner, feel the steering, the brakes and the engine response, and have a pretty accurate idea whether it meets our standards. If it doesn’t, we work harder.”
As we continue to storm the circuit, it suddenly strikes me why Weissach’s blurring walls are so necessary.
Besides deterring scoop cameramen, they underscore the fact that Porsche’s famous site, half an hour west of Stuttgart, is increasingly packed with the kind of buildings a company like Porsche needs to design and develop a high-performance car range it can sell to the tune of 200,000 each year.
And even if more than three-quarters are SUVs and saloons (“every Porsche is a sports car in its class”), selling high-value cars in such numbers in so many markets is a helluva task. No one else comes close.
Hatz is careful not to claim the 918 Spyder concept as his own. The model was born in winter 2009 and revealed as a concept at the 2010 Geneva show, just before he returned to Porsche.
But Hatz is very definitely the bloke whose teams had to bring it to life.
At the outset, he thought it “a slightly crazy idea”, knowing secretly that the show concept was really a Carrera GT underneath and the promised world-beating hybrid mechanicals were ideas, not hardware.
“It was a bit like the Americans announcing they were going to the moon. Telling the world is easy, but then you have to do it.
"In the beginning, it was really hard. Every day I’d be in the workshops explaining to our engineers that we had to fly to the moon. But we did it, and I’m so proud of what we achieved.”
Then, of course, there are Porsche’s race cars.
Weissach is where Porsche has bred a distinguished line of competition cars over many decades, the latest being the 919 Hybrid sports-racer that last year (at Hatz’s instigation) put Porsche back into the top echelon of endurance racing for the first time in years.
It might even have won this season’s first event at Silverstone but for the failure of a trifling component buried in its rear differential.
As soon as Hatz and his racers had returned, they huddled in the workshops, chasing reasons for the failure. It is most unlikely to be repeated.
“When I came back to Porsche, it was clear from day one we had to be in top-level racing,” he explains.
“But we had to prepare. My former connections in F1 helped me know where the good people were – I spoke to Mark [Webber] back in 2011 about us doing it together – and we needed new buildings if we were going to do it properly.”
Since then, Porsche’s chances of success have only increased.
Interestingly, Hatz is at his most reassuring on future technology. On his watch, Porsche has started offering plug-in hybrid versions of several models (Cayenne, Panamera and 918 Spyder so far) and more are coming.
“We cannot ignore the need to reduce our output of greenhouse gases,” he says, “but we must also make true Porsches.”
Hatz does not shrink from the complexities of the future.
In fact, he is remarkably reassuring on the future of high-performance Porsches, even as hybrids, electrification and small-capacity engines come increasingly to prominence.
“Don’t worry about our ability to keep making great cars,” says Hatz.
“We will do it. The 918 is our best answer to any concerns our customers may have about the future. With us you are safe. In the future, we will have the technology.
"Whatever happens, we will have the answer.”
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