‘Parts that could not stand the extreme loads were re-made’

Engineering-in reliability requires an intense testing regime, as veteran Porsche test driver Dieter Röscheisen explains

Dieter Röscheisen was a Porsche engineer and test driver for more than 40 years, beginning in 1976. ‘From the very beginning, our goal at Porsche was to build great and reliable cars that thrilled the customer,’ he says. ‘It has always been like this. Compared to other automobile companies, we were a small family company, with short decision-making paths. We had excellent and decisive bosses, so we could quickly implement everything.’

Engineering that reliability into the cars began before they were ever built. ‘All new components were tested on different test rigs,’ says Röscheisen. ‘Then the parts were installed in various prototypes and tested in the vehicle. Very important for us were two endurance tests, which each new development had to go through and survive without damage.’ The first, carried out at Porsche’s own Weissach test track, was 3750 miles (6000km) on a washboard surface which could quickly simulate 75,000 miles (120,000km) of real-world driving.

‘It’s extremely hard not only for the vehicles but also for the drivers,’ Röscheisen says. ‘The drivers changed every hour and every 1000km there was a general check, where the body and all other components were inspected for damage and cracks. Parts that could not stand the extreme load were reworked, re-made and re-tested in the next endurance test.’

If a prototype survived that it would go on to an 80,000km (50,000 mile) test on public roads around Stuttgart. ‘We worked three shifts – the morning on country roads, the afternoon in city traffic and the night shift on fast roads. For chassis and tyre tests we went to the Nürburgring Nordschleife, while high-speed testing, lane change tests and brake tests were done at Nardo in Italy or Ehra-lessien in Germany. For wet-road handling tests we went to Continental’s Contidrom track near Hanover, Dunlop’s track at Wittlich near the Luxembourg border or Goodyear’s at Mireval in France. Steep hills were needed for brake tests, so we took prototypes to the Grossglockner in Austria, the Stelvio pass in Italy and Mont Ventoux in France. We carried out heat and dust testing in Algeria, the USA and Canada, while control systems and ABS were tested in sub-zero temperatures at Arjeplog in Sweden. We tested snow tyres at Turrach in Austria.

‘In the case of a good test driver, driving on the limit must be absolutely secondary, so that he can concentrate fully on the driving behaviour and the various components,’ says Röscheisen. ‘A technical education is also very important. Only if one understands the technology, can one give the constructors the correct feedback.’

Despite their miraculous car control abilities, racing drivers often don’t make great test drivers, he says. ‘They are used to always looking at the stopwatch, so anything that is fast, they will find it good. It does not matter if breakaway is abrupt – a good racer gets along with it. The main thing is the lap time is fast. For a road car, lap times matter less than progressive handling. Here it is important that breakaway must be gentle and announced to the driver in good time. Only then will the normal driver cope and enjoy driving. The car has to be easy for every driver to drive and control.’