It's set to be a battle of wildly-different drivetrain technologies at the 2012 24 Heures du Mans, which gets underway this weekend (16-17 June) at the illustrious Circuit de la Sarthe.
With Peugeot having dropped its endurance racing programme due to budget concerns, this year's headline battle will be a straight fight between the dominant diesel Audis, and petrol Toyota newcomers.
Surely it'll be yet another Audi victory at Le Mans in 2012?
The statistics would concur - Audi have won 10 outright Le Mans victories since 2000, only losing out to fellow VW group member Bentley (2003) and arch-rival Peugeot (2009).
The all-conquering diesels will return in the shape of the R18 Ultra and new R18 E-tron Quattro – but they'll be facing a strong challenge from newcomers Toyota with their TS030 Hybrid.
What are the details on Audi's R18 Le Mans competitors?
Audi are running two R18 Ultras at Le Mans this year, and two E-tron Quattros. The Ultras feature a 532bhp 3.7-litre turbodiesel V6, and are overall very similar to the R18 which won (and those which crashed out spectacularly) during the race last year, albeit lightened thanks to a carbon gearbox housing and monocoque alterations.
The E-tron Quattros on the other hand, are a significant development on the R18, entering as the world's first hybrid diesel LMP1 cars. As the name suggests, they boast all-wheel-drive, thanks to a flywheel-powered electric motor that sends drive to the front wheels at speeds over 75mph.
The increased fuel efficiency at high speeds, and traction through turns, is likely to make the Audis standout performers in this year's race – and the team are confident lessons learnt at the racetrack will advance the development of electrically-powered Audi road cars – though not the A1 and A2 E-trons, the death of which CAR revealed earlier this month.
How do Toyota plan to challenge the Audis at Le Mans?
Toyota will fight the headline LMP1 (Le Mans Prototype) class with its TS030 – also a hybrid – though not four-wheel-drive, and not diesel. Instead, the TS030 uses a 3.4-litre normally-aspirated petrol V8, and a regenerative-braking-powered electric motor which also sends its drive to the rear wheels.
By not gaining a traction advantage from all-wheel-drive, Toyota are allowed by the regulations to use their electric boost at any speed, rather than above the 75mph limit Audi are restrained by.
The Toyota effort may sound plucky, but there's more to it than have-a-go hopes: despite a testing crash at Paul Ricard circuit which damaged the monocoque beyond repair, an all-new car has set competitive testing times at Le Mans just one second behind the best the Audis could manage. Ingolstadt's next endurance title might not be quite in the bag just yet...
Former F1 driver Anthony Davidson will be driving for Toyota, having previously competed for Aston Martin and Peugeot in the elite LMP1 class. The 32 year-old Brit has lauded the 206mph TS030's powertrain reliability, though he admits it's not an easy car to drive. 'Unless you’ve been shown how to operate the car you can’t even get it out of the pit box. Actually, I had a bit of trouble the first time I drove this car because LMP1 cars nowadays are so complex you really have to read an instruction book before you get behind the wheel.'
Davidson also acknowledges the risks of racing with 56 cars on track of wildly different abilities - something no doubt fresh in Allan McNish's mind after his R18's horror shunt with a slower Ferrari 458 in the opening stages of the 2011 event.
When does Le Mans take place?
The 80th 24 Heures du Mans will begin at 3pm (2pm UK time) on 16 June 2012, and finish - you've guessed it - at 3pm on Sunday 17 June. Alongside the Le Mans prototypes there'll be more familiar-shaped machinery in the GT classes, with the likes of Aston Martin, Ferrari and Corvette vying for glory at the world's oldest endurance racing event.