Le Mans 24 Hours Test Day
Trying To Understand The Numbers

Thanks to José Luis Garcia and his colleagues at Al Kamel Systems, providers of the timekeeping service at Le Mans, a great deal of data became available immediately after the red flag flew, bringing the Le Mans Test Day to a slightly premature close just minutes before 6pm on Sunday. Although, as uncompleted laps at that time had to be aborted due to the red flag, the possibility remains that some cars would have been in a position to improve, had Enzo Potolicchio not crashed at the Dunlop chicane.

So despite, for family reasons, being unable to be at the Test Day, it was possible for me to follow what was going on, and more importantly, to analyse some of the less obvious results.

Hence, I know that Elton Julian was fined €2,000, Christoffer Nygaard €1,400, Bertrand Baguette €800, Fabien Barthez €4,200, Yelmer Buurman €1,000 and Stuart Hall €400 for speeding in the pit lane during the morning session.

Perhaps it is more interesting though to look at what was happening on the track. Of particular interest this year is the way that fuel consumption will affect the race. For this year’s race, fuel capacity aboard LMP1 cars has been reduced, such that the diesel-engined Audi R18 ultras may only carry 60 litres, and the hybrid e-tron quattros only 58 litres. (Compare that to 1955, when cars were permitted 200 litres of high-octane petrol!) The hybrid Toyotas, being petrol-powered, are allowed 73 litres.

So what does that mean in terms of numbers of laps? Last year, in the intense Audi vs Peugeot battle, the Audis (then with 65 litres of diesel aboard), could comfortably manage 11 laps, but not 12 unless there was a full course caution.

So I was a little surprised this year that the Audis managed 12 laps without refuelling on a number of occasions.

The number 1 Audi managed a 12 lap stint at the end of the morning session. The number 2 did one at midday, and shortly aftwards, the number 3 non-hybrid, with more fuel and less-efficient technology managed 2 stints of 12 laps as well. Marco Bonanomi, in the non-hybrid, (run by Howden Haynes) did his 12 lap stint ‘straight out of the box’ after a single installation lap when the green flag flew at 9am. Oliver Jarvis did another 12 lapper before lunch.

Straight after lunch, André Lotterer did 12 laps in number 1, but Audi’s programme now moved on to other things.

Over at Toyota, only one stint was of 12 laps – set by Sébastien Buemi in the no. 8 car in the afternoon session. Crucially, though, the safety car made its appearance on track during this stint, so the average lap times during the stint went up significantly. Without the intervention, would the Japanese cars have been able to do a full 12 laps? On the evidence of last Sunday, I would suggest not.

One of the great fallacies of Le Mans, however, is that saving fuel at the expense of lap time, and spending less time in the pits, is a formula for success. Greater pace will usually see you ahead of a slower, but more economical car. The average lap times for these stints are therefore interesting to examine.

Note especially that final average lap time from Lotterer – after the lunch break. This included a lap time of 3m 27.167s, and moreover was on a slightly damp track! In 2011, the fastest stint of the race was ten laps from Tréluyer with an average lap time of 3m 28.7s. Bear in mind how the nature of the Le Mans track is to improve over race week, as the rubber goes down: it is clear to me, that this year’s Audi is a substantial step forward – with or without hybrid technology. If a 2012 Audi is capable of completing an extra lap with 7 litres less diesel on board, without reducing its pace, then surely a faster lap time would be possible if a less economical engine mapping were used?

Allan McNish’s fastest lap of the two sessions – 3m 25.927s – is remarkable compared to last year’s fastest time during the test day of 3m 27.687s. On that basis, this year’s pole lap could be in the 3m 22s bracket.

What about the pace of the Toyota though? Even though neither of the petrol hybrids completed a full 12 lap stint, there were some 11 lappers that can be used for evaluation. In the morning, Kazuki Nakajima did 11 laps at an average of 3m 39.3s and Nicolas Lapierre an average of 3m 33.7s. After the lunch break came an 11 lap stint from Anthony Davidson at an average of 3m 36.7s.

Slower than Audi, yes; but not embarrassingly so, especially when you consider how much steeper is the Toyota learning curve, despite the presence of the Oreca expertise in the garage. For the sake of the race, let’s hope that the reliability is there.

Where might the petrol privateers be? A petrol LMP1 last year could manage 12 laps on a 75 litre tank of fuel. With the same fuel allowance this year, none of the stints from the Test Day suggest that sufficient improvements in fuel efficiency have been made to permit an additional lap to be completed. In terms of lap times, the fastest privateer lap time this year came from the Strakka HPD with a time of 3m 34.243s – more than two seconds faster than last year’s fastest privateer, but still substantially slower than the works Audi or Toyota times.

In terms of long stints though, the longest stint for Piers Philips crew at Strakka Racing was just seven laps for the HPD: that is well short of a full tank of fuel. Indeed, neither of the HPDs really completed enough laps to enable sensible average lap calculations.

The two Rebellion entries both completed 12 lap stints on several occasions – the same as last year, and average lap times for both were within a few tenths of one another at around 3m 43.3s.

In comparison, 2004 winner Seija Ara, at the wheel of the Pescarolo Dome did 11 laps at an average of 3m 47.5s.

In summary, it would seem that the order is clear: Audi, Toyota, Rebellion, Pescarolo. Without the inevitable intervention of safety cars, 16.5 laps an hour would be possible - on a dry track. For a record distance, 398 laps would be needed. Unlikely, but just possible, despite the restrictions that face the cars these days.

Sebring provided a great battle in LMP2, and at Le Mans a close race is also in prospect. New regulations have helped to improve the reliability of cars in the class, but working out who might come out on top over twenty-four hours is more complex because of the requirement for a silver/bronze graded driver on the roster, and the need for this driver to complete at least four hours of the race.

In the following table, I show the average of the top three times from each driver in each of the LMP2 cars that participated in the Test Day with three drivers.

Finally, note that the other three LMP2 cars were only driven by two drivers, so I have not included them in this list. These were the no. 33 Level 5 Motorsports car (not driven by Scott Tucker), the no. 35 Oak Morgan Nissan (not driven by Jacques Nicolet) and the Norma.

With just days before the start of official qualifying, many questions remain to be answered. But some important ones have already been answered, if you start to dig under the surface of the numbers from the Test Day.

Paul Truswell