Porsche is responsible for two of the biggest upsets of the century in North American sports car racing. The first, at the 2003 Rolex 24 At Daytona, was produced as the former Grand-Am Rolex Series introduced its new Daytona Prototype formula which, thanks to absences of speed and reliability, made an overall win possible with a Porsche 966 GT3-RS.

As DPs faltered or failed, second-tier GT cars moved up the running order until The Racer’s Group held a commanding lead and won with a 56-mile margin of victory to the closest prototype. And while Daytona 2003 is remembered for the alarming overall win for a GT car, it also came at the dawn of a new prototype category, where struggles for the unproven DP models were anything but a surprise.

The second overall win, taken five years ago at Petit Le Mans, was the real shocker as the factory Porsche GT Team mollywhopped the entire field with sheer pace. Run under heavy rainfall for most of the 10-hour contest, the rear-engine Porsche 911 RSRs were perfectly suited for the treacherous conditions. And thanks to Michelin’s presence in IMSA’s GT Le Mans class, the rest of the grid — saddled with uncompetitive rain tires from official series supplier Continental — were in for a humbling day and night at Road Atlanta.

So, with the 2020 edition of Petit Le Mans here to enjoy, let’s take a long and detailed look back at the 2015 race where England’s Nick Tandy, France’s Patrick Pilet, and Austria’s Richard Lietz made history while embarrassing DPs, LMP2s, and 30-plus entries who were helpless to stop the No. 911 Porsche 911 RSR from conquering all comers.

NICK TANDY: “Obviously, we had the forecast and we could see there was a likelihood of rain for the race day, same as everyone else. But going through practice you tend to always try to set a car up for dry conditions, mainly. Because you never know how the forecast can change and you can always run a wet race with a dry setup, but it’s very difficult to be competitive in a dry race if you’ve got a full wet setup on the car.

“We planned basically for setting the car up for a dry race, and (at) the (wet) night (practice) session we got some running, but we knew from previous times that we’d run in the wet that year, on the tire that we had, that basically going out and putting a wet tire on a dry set up, the car was always pretty good. Which is obviously what you want your wet tires to be, to work at, so we got a bit of practice.”

Porsche was one of few teams to use the rainy night practice to work on rain chassis setups.

PATRICK PILET: “(It was) confidential tires like we use in WEC, because at this time it was these kinds of tires we use for all GTLM. This tire was mega in the rain — it was really, really good. We had a night practice and I remember at this time it was pouring a lot and there were not so many cars driving because it was a lot of aquaplaning. I remember at this time we decided to cut the tires because we can make extra grooves when it’s a lot of water just to get a less aquaplaning.

Porsche’s night setup work was put to good use. Image by Marshall Pruett

“I was in the car at this time in the night just at the end — nobody once really asked to drive because it was really difficult conditions. We just say, ‘OK, let’s just try to see if it’s really efficient or not’ and it was — it was really good. So we kept this in mind this, and later in the race it was something really important.”

With a two-car team to prepare for the race and a GTLM championship on the line, a hard crash by Earl Bamber in the sister No. 912 RSR in qualifying stressed the teams resourced prior to the race. The No. 911, with Tandy on board for qualifying, also faced adversity when in post-session technical inspection, the car’s front ride height was found to be below the minimum allowed in the rules. Despite showing front-running pace, both cars were sent to the back of the field for the start — one for an infraction, and the other due to a chassis change as a result of the damage done to the next to the No. 912.

PILET: “Just to qualify was also in difficult conditions. If I remember well, Earl (Bamber) was on the pole, Nick was P2; unfortunately Earl had a big crash. To be honest, at this time in qualifying, it was more or less the guy would take the most of the risk (would take pole).”

With Petit Le Mans serving as the 2015 season finale, Porsche’s IMSA program manager says the only matter of interest entering the event was securing the drivers’, teams’ and manufacturers’ championships. Holding a tiny advantage over the BMW Team RLL outfit and the No. 25 BMW Z8 meant any issues in the race for the No. 911 RSR crew would hand the titles over to their German rival.

STEFFAN HOLLWARTH: “It was not only the weather forecast that was a concern, but also all the three championships were still not decided. And we headed into the weekend with only a three-point gap to BMW and the 25 car. This is something where everybody was a bit nervous before getting into the event.”

TANDY: “Well, yeah, this is it. So we had all the stress on, it must have been the Friday night after the qualifying, because the team had to re-tub the 912 car, so it was late and stressful for them. And then basically as soon as everyone got up early on the Saturday for the race, it became pretty clear that it was going to be pissing down all day, which is how it turned out. Road Atlanta is one of those tracks where you make a small mistake, you have a huge accident. You don’t often see small crashes at Road Atlanta.

“You put a couple of wheels onto an exit curve, something like this early in the race, it’ll be game over for sure. So, yeah. Going into that race, our mindset was to get through the first eight hours. And we knew from previous experience that our car and our tire was good against our GTLM opposition. Even though we were starting right at the back, there wasn’t really a lot of stress. We were just cruising around. And, as Patrick mentioned earlier, even driving on the straight and the aquaplaning, it was the risk of something happening or making a mistake was huge all the time. Even if you’re just driving around at 90 percent, the concentration needed to keep the car on track and make sure that nothing happened was huge. So it was not your typical start and preparation to a long endurance race.”