24-hour hybrid hell at Le Mans

LE Mans has become a test bed for the cars we will drive tomorrow.

The Toyota TS040.

THE film Le Mans regularly makes top-10 lists of car movies, but that’s mainly because other motorsport films are so bad. Despite starring Steve McQueen and lasting less than two hours, the film is a test for anyone who doesn’t already love motor racing. It’s thin on dialogue, long on action.

But that pales beside the challenge of the race itself and last weekend, for the 82nd running of the Le Mans 24 Hours, revised rules meant it reasserted its importance as a test bed for technology and clash of brands.

LE Mans is a charming French city that comes alive for the event, with a crowd of almost 300,000 including thousands of enthusiastic British.

The race is a round of the recently formed World ­Endurance Championship, with seven other rounds of six and 12-hour events at tracks such as Silverstone in Britain. But Le Mans is the prize and there’s a reason: it’s a test of driver and machinery unlike any other.

A single Le Mans race is equivalent to almost an entire season of Formula 1, with the fastest cars covering around 5000km and hitting 330km/h an hour. Average speeds reach 200km/h and above.

The track is so long — more than 13.6km — that the weather can vary wildly over a single lap and there’s a mix of surfaces, with much of the circuit a public road for the rest of the year. Driving through the night adds another level of challenge, even with three drivers each taking stints. Overtaking manoeuvres are constant as the quicker cars round up the slower entries and it makes for a fascinating spectacle, with darkness adding another level of drama.

The winner needs to avoid incidents while driving consistently fast for 24 hours with a minimum of mechanical trouble.

GRAPHIC: The Le Mans 24 Hour circuit

UNLIKE, say, Formula 1, a variety of cars race simultaneously at Le Mans. The slowest are GTs — racing versions of road cars. This field is dominated by Porsche 911s and Ferrari 458s, with Chevrolet Corvettes and Aston Martin Vantages in smaller numbers.

The quickest two classes are Le Mans Prototypes, LMP2 and LMP1. These are purpose-built racers and the fastest closed-wheel cars on circuits anywhere.

LMP2 offers scope for private race teams to enter at a high level while the fastest LMP1 category attracts manufacturers. Rule changes that came into force this year mean fuel efficiency is now as important as performance and reliability in winning. Manufacturers must use ­hybrid drivelines and there’s plenty of scope for a variety of approaches, with complex formulas governing the amount of fuel and energy permissible per lap.

As more and more brands are embracing hybrids, ­including the latest generation of supercars, it’s opened the door for technology transfer into road cars.

And it’s worked, with the rule changes bringing carmakers back to the event.

AFTER being dominated by Audi for more than a decade, this year saw the return of Porsche, which has won Le Mans more than any other brand, after a 16-year ­absence. Toyota is now in its third year while Nissan ­enters the fray in 2015. There are even rumours Ferrari is considering an LMP1 entry.

Porsche’s entry, the 919 Hybrid, was designed from scratch in little more than two years and boss Matthias Mueller is clear about the brand’s motivation.

“The new and revolutionary efficiency regulations for this class were what prompted us to take this step,” he says. “It is not going to be the fastest contender who is going to win … but the car that gets furthest with the ­defined amount of energy.

“And it is precisely this challenge that the automotive industry has to face. The 919 Hybrid is like a high-speed research laboratory and the most complex racing car Porsche has ever built.”

Porsche already had a hybrid road car underway in the 918 Spyder and the racing team learned from it.

Australian driver Mark Webber left Formula 1 to drive for Porsche and says cross fertilisation was vital.

“There’s a lot of 918 stuff in the 919,” Webber says. “It was almost the cart before the horse! It helped us a lot.”

THE rules are so flexible each maker has come up with a different solution.

Porsche flags its intention to return to four-cylinder engines by using one in the 919 — a turbocharged 2.0-litre V4. It’s unusual in recuperating energy from two sources on the car: brakes and the exhaust gas from the turbocharger. They feed lithium ion batteries which then power an electric motor driving the front axle.

During the race, it generates enough power to drive an electric hatchback more than 4500km, Porsche says.

Toyota’s TS040 takes a different approach with a 3.7-litre naturally aspirated V8 plus electric motors front and rear. Energy recovered under braking is stored in a supercapacitor rather than batteries.

It’s Toyota’s third attempt to win Le Mans with a ­hybrid after competing in 2012 before the rule changes came into effect. Team chief Yoshiaki Kinoshita says the changes make endurance racing the most road-relevant discipline in motorsport.

“We are competing in order to test the latest hybrid technology in the most extreme motorsport environments, and this has a direct influence on future road-car technology,” he says.

Audi’s solution is different again, evolving its hybrid race car which has already chalked up two victories. It also builds on previous Le Mans success with diesels, using a turbocharged 4.0-litre V6 diesel engine backed up by an electric motor at the front axle. Energy is captured under braking and it chose mechanical storage by using a flywheel.

Audi believes it has found the right solution. “In our opinion, it provides the optimum balance between ­efficient energy use, size, weight, energy conversion ­efficiency, responsiveness, driveability and a favourable operating strategy — combined with durability, which is the basic prerequisite for success at Le Mans,” Audi motorsport boss Wolfgang Ullrich says.

If the solutions are already remarkable in their variety, then they will only be more diverse when Nissan returns, according to executive Andy Palmer.

“All our rivals in the class have taken different technical approaches and we will be doing the same. We want to win in a very different way to that of our rivals.”

DESPITE the contrast in approaches, the racing was desperately close, with Toyota taking pole and leading with its superior outright speed. After a crash hurt Toyota’s chances it clawed its way back to third.

Webber’s Porsche led the race with just two hours to go, but was undone by an engine problem to leave Audis in first and second.

With more manufacturers next year the most famous race of all promises to be even better — and even more relevant to sportscars of the future.

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NEED TO KNOW:

LMP1

The premiere class at Le Mans saw three manufacturers teams fighting it out with different technical approaches to producing a racing hybrid.

Porsche 919 Hybrid

Construction: Carbon-fibre composite over aluminium honeycomb core, carbon brake disks, magnesium wheels

Driveline: 2.0-litre turbocharged V4 petrol driving the rear axle, electric motor at front axle (more than 550kW total), seven-speed sequential gearbox, all-wheel drive

Energy capture: Brakes and exhaust

Energy storage: Lithium ion batteries

Toyota TS040

Construction: Carbon fibre, carbon brake disks, magnesium wheels

Driveline: 3.7-litre naturally aspirated V8 petrol with electric motors front and rear (736kW total), seven-speed sequential gearbox, all-wheel drive

Energy capture: Brakes

Energy storage: Supercapacitor

Audi R18 E-tron Quattro

Construction: Carbon-fibre composite and aluminium, carbon brake disks, magnesium wheels

Driveline: 4.0-litre turbocharged V6 diesel driving the rear axle, electric motor at front axle (undisclosed kW total), seven-speed sequential gearbox, all-wheel drive

Energy capture: Brakes

Energy storage: Flywheel