2011 marks almost certainly the biggest shift in LMP1 regulations since Audi showed up with the diesel fuelled R10 TDI in 2006. Ever since the diesel revolution stomped its authority on the 12 Hours of Sebring when Dindo Capello, Tom Kristensen and Allan McNish took the R10 to victory on its race debut a diesel has won every year at Sebring.

The Automobile Club de l'Ouest have tried ever since to shackle the diesels – smaller fuel tanks, smaller restrictors – but Audi and Peugeot have always been able to keep their advantage.

This season could change that. As well as the new aerodynamic regulations, headlined by a sharkfin engine cover, designed in an effort to stop the sort of flips that have effected LMP1 machinery in recent years, there are changes in what will power the cars. Peugeot's new 908 – which will debut at Sebring – is powered by a 3.7 litre engine producing only 550hp, compared to the stated 700hp developed by the 5.5 litre heart that propelled its predecessor. These same limitations affect the petrol powered runners, Rebellion Racing, for example swapping a 5.5 litre Judd engine for a 3.4 litre Toyota unit to lead the manufacturer's engine program.

That said Sebring, and 2011 in general will be a strange mix of the old and new. While Peugeot's two works crews will be in the new 908, Team Oreca Matmut – returning as the marque's privateer partner – will have an old 908 HDI FAP. Audi, despite having the brand new R18 waiting in the wings will run with the older R15+, simply tweaked to the new specifications.

With Aston Martin Racing's new AMR-One missing from the entry list Muscle Milk AMR's Lola-Aston Martin will be responsible for keeping up Aston's record as the nearest petrol challenger to Audi and Peugeot. They will, however, face strong competition from two other Lola chassis, Rebellion's Toyota powered example and Dyson Racing's Mazda engined, older chassis.

Also on track will be a pair of OAK Racing Pescarolos – the French team bring two cars after debuting in America with a single car at Petit Le Mans – and the HPD ARX-01e of Highcroft Racing.

Highcroft's car is a quirk. Based around the same tub and engine as the LMP2 01c which won both the American Le Mans Series title and Le Mans 24 Hours in 2010, it is, perhaps, the ultimate evolution of an LMP2 chassis, with a comprehensive new aerodynamic and suspension package to bring into line with the LMP1 specifications.

No.1 – Audi Sport Team Joest – Audi R15+
Timo Bernhard-Romain Dumas-Mike Rockenfeller

Audi have chosen to give the R15+ the Sebring it didn't get in 2010 and the three drivers that won at Le Mans last year are given the honour of the no.1 plate to begin the Intercontinental Le Mans Cup (ILMC). Whether or not you think the combination of Porsche works drivers Dumas and Bernhard and Audi DTM regular Rockenfeller are the strongest combination in the class, the Audi R15+ they will drive has pedigree enough (and a diesel engine) to make it an automatic contender for victory.

“The key to a good result will be getting through the traffic without problems for 12 hours,” Rockenfeller says. “We'd certainly like to present the Audi R15 TDI with exactly this in its final outing. For Timo [Bernhard], Romain [Dumas] and me it is also an important part of our preparation to compete once again as a trio of drivers. After all we'll also face the competition in this formation at Le Mans.”

 

No.2 – Audi Sport Team Joest – Audi R15+
Dindo Capello-Tom Kristensen-Allan McNish

Probably the strongest driving trio in the class – if not the grid – are another team you have to consider will be racing for the win if the car holds together better than it did under McNish at Silverstone last September, where an early retirement cleared the way for Peugeot domination.

The car will be central to the outcome of the latest Audi v Peugeot clash. During testing McNish told thecheckeredflag.co.uk that no extra development work has been done on the car, other than bringing it up (or should that be down?) to 2011 specifications. Whether this square peg into a smaller square hole approach results in a poor compromise s yet to be seen, as is how it will stack up against the new 908 – a car designed specifically for the new rules, but without the R15s race results behind it. Old versus new will be the story of the lead in LMP1.

No.7 – Peugeot Sport Total – Peugeot 908
Anthony Davidson-Marc Gene-Alex Wurz

The last twelve months of Peugeot have been up and down. Victory (though almost unchallenged) at Sebring last year was followed by winning the 100km of Spa, which preceded a disastrous (and tearful) Le Mans when all four HDI FAP machines retired – three with similar engine problems. The year ended on a high, taking all three races that formed the ILMC last year.

So, with a 100% record to defend they arrive at Sebring with a new car, and one that has had its development punctuated by significant crashes have Peugeot taken a leap of faith to begin with one of the toughest races of the sportscar year?

No.8 – Peugeot Sport Total – Peugeot 908
Pedro Lamy-Franck Montagny-Stephane Sarrazin

Peugeot's two line-ups, in theory, are more equal than Audi's, though this trio have, arguably, a slight edge over their teammates. Of course the, like their teammates and the two Audis they are legitimate shouts for victory. However, a difference appears between Audi and Peugeot is evident when comparing the approach to the race.

While Audi are all about one last hurrah for the R15 – a race nothing before the R18 program hits a competitive track – Peugeot are still developing the car with all thoughts already on Le Mans.

“We'll be following our specifications,” says technical director Bruno Famin, “aiming to complete the full 12 Hours so we can rack up plenty of track time and thus acquire valuable information about the car. We also need to learn how to get the best out of it.”

No.10 – Team Oreca Matmut – Peugeot 908 HDI FAP
Loic Duval-Nicolas Lapierre-Olivier Panis

If, and despite quotes from Famin, Olivier Quesnel and company it's still an 'if', the new 908s are on a glorified long distance test run then Oreca's older car might be the horse Peugeot back for victory.

Like the Audis the HDI FAP has had to be squeezed into the new LMP1 restrictions, Oreca having tested with the smaller restrictor and lower boost pressure that will strangle the 5.5 litre engine.

Despite coming off badly second best the last time Hugues de Chaunac's team were leading the Peugeot charge – at Paul Ricard eleven months ago – in Duval, Lapierre and Panis the team have three drivers familiar with the car, if not Sebring, and have the potential for rapid pace. Duval's desperate drive, as the only remaining Peugeot, was one of the stints of the race before it ended in fiery retirement. If he, and his teammates, are unfettered again they could push Audi for victory.

No.12 – Rebellion Racing – Lola-Toyota
Jeroen Bleekemolen-Neel Jani-Nicolas Prost

Below the quintet of diesels the race for best petrol LMP1 car is wide open. Rebellion were regular claimants of the win in the unofficial class in 2010, and now with a modicum of factory backing thanks to Toyota's racing engine program the Swiss based team enter 2011 ever stronger.

Bleekemolen – joining Jani and Prost as third driver – won LMP2 at Le Mans in a Porsche Spyder in 2008, and so brings ample ability in wheeling a prototype as well as the GT Porsches he, and brother Sebastiaan are more familiar in.

“Most important is that we want to compete for the win, it is a tight and twisty circuit that should be well suited to our car and we should be able to challenge the diesels there,” says Prost. “We do not yet know whether the new equivalences have levelled the gap between the diesel and petrol engine cars, Sebring will give us an initial view of that.”

No.15 – OAK Racing – Pescarolo-Judd
Matthieu Lahaye-Guillaume Moreau-Pierre Ragues

Since OAK Racing, then called Saulnier Racing, brought LMP2 Pescarolo chassis to Le Mans in 2008 the French team have finished on that class' podium every June, the increasing scope of the team's ambitions clear in their position as the only LMP2 team to take part in the ILMC last year.

2011 brings a new challenge. After team owner Jacques Nicolet was part of the group that put Henri Pescarolo back at the head of his own team, OAK Racing are taking on LMP1. Laheye and Moreau move up a class with the team, while Ragues comes in after racing with the Signature squad in LMP1 in previous seasons.

However, with a relatively inexperienced driving line-up and the oldest car in the class, the 01 chassis dating back to 2007, there is a chance that LMP1 at the highest level is just an ambition too far.

No.24 – OAK Racing – Pescarolo-Judd
Richard Hein-Jacques Nicolet- Jean-Francois Yvon

Just as in recent years OAK Racing have two car, the no.15 the 'racers' car and the no.24 a far more gentlemanly affair.

Don't expect the no.24 to be the fastest in qualifying, or to put in the fastest laps in during the race, but if the car doesn't fall apart beneath them expect them to be there at the end. A podium, albeit in a new class, is near impossible but there's an outside shot of ending as best petrol car.

No.01 – Highcroft Racing – HPD ARX-01e
David Brabham-Marino Franchitti-Simon Pagenaud

If any car and team has the ability to surprise the diesels it might be Highcroft and the new LMP1 HPD. In Brabham and Pagenaud Duncan Dayton has two of the best drivers who won't be aboard diesels in Florida, and Franchitti is a worthy third man.

Highcroft and HPD know Sebring, and what it takes to survive the race and the drivers have been glowing in their praise of the reworked car.

“It is a lot faster in the straight and certainly way quicker than what we are used to in this car,” said Brabham. “That was really exciting to see. We're low on downfoce but we're waiting for the grip to come up during the week as we discover what the balance is like, getting the ride heights where they need to be – there is so much for us to do, but we are really just getting started.”

The only worry is that there is just enough new car bolted onto the tub from the LMP2 car to throw up enough new things to go wrong, especially with testing limited before the race. With that in mind it is worth thinking back to when HPD (or Acura then) debuted the LMP1 02a at Sebring. When both cars were mired in problems all race.

No.06 – Muscle Milk AMR – Lola-Aston Martin
Klaus Graf-Lucas Luhr-Greg Pickett

The off-season has seen Pickett's team trade the Porsche RS Spyder in for the Aston Martin closed coupe, but keep German Luhr in the driving team, despite his historic ties to Audi and Porsche machinery.

The step into LMP1 – like OAK and Highcroft before them – puts them in a very competitive field. The car is proven – in works hands – to be capable of winning the petrol race, though never being close to really threatening the diesels. Graf and Luhr can deliver the pace necessary to continue to challenge for best petrol under the new ownership, Pickett is the weak link – a gentleman driver in a very professional class.

If the team are serious about challenging the upper reaches of the leader board it will be the German duo who do much of the driving, Pickett's stints – when they do come – will be critical.

No.016 – Dyson Racing Team – Lola-Mazda
Jay Cochran-Chris Dyson-Guy Smith

Almost forgotten, at the end of the class entry list, are Dyson Racing. Beneath the ILMC entries and the new HPD and Pickett's Aston are the other ALMS prototype regular. Smith and Dyson are regular drivers, joined by Jay Cochran, a veteran who, in Dyson's words “brings speed, experience, a good track record, and full commitment to the team.”

Perhaps more so that the other American teams Dyson face an uphill struggle in an enlarged LMP1 class. “The car feels comfortable,” Smith noted after winter testing. “We are adapting to the rules changes that give us less power and more weight. The team has done a good job with the chassis to accompany the extra weight as well as AER with the Mazda engine in making the car drivable with the power level we have.”

“Comfortable” may be the watch word for Dyson Racing, likely to be steady and unspectacular in the face of tough opposition and a car in transition.