The 2010 Le Mans 24 hour classic will be the last chance to see the big banger turbo diesels in action.

Changes to regulations for 2011 and beyond are expected to cut the maximum engine size of the diesels back to only 3.7 litres a far cry from today’s 5.5 litre 700 BHP powerplants.

Already the two major players in the diesel race at Le Mans have signalled their intention to develop cars for the new regulations.

According to the respected magazine Racecar Engineering, Audi will develop a new car powered by a 3.7 litre Turbo V6 while Peugeot have announced that they are actively developing a hybrid powered racer to replace the current 908 HDI FAP.

A hybrid version of the current car was developed and displayed at several events, however Peugeot Sport bosses have put a hold on all further development of that car so that the team can concentrate on defending it’s Le Mans title in 2010 and designing and building the new car.

Meanwhile Porsche have unveiled their first Hybrid racer a version of the venerable GT3 which will race in the 2010 VLN series including the Nurburgring 24 hours.

Unlike the Peugeot which will use batteries to store energy, the Porsche uses a flywheel system that was developed for F1 by Williams but never used.

The new GT 3 R Hybrid features an electrical front axle drive with two electric motors each developing 60 kW. This supplements the familiar 480 hp four-litre flat-six ‘boxer’ petrol engine at the rear.

Consequently, the 911 GT3 R Hybrid has four driven wheels, offering even greater traction and agility.

The potential of the new technology has already spooked Peugeot who have called on the ACO to ban it from Le Mans.

The flywheel technology is simplicity in itself and provides all the benefits of hybrid power but without the huge weight penalty of carrying large batteries.

For the ACO, this presents a considerable problem.

The club has, through it’s innovative engine rules, pioneered the use of diesel as a viable racing fuel. It has once again brought Le Mans back into the mindset of major auto manufacturers looking to test and develop new performance technology in the toughest racing environment in the world.

Banning Porsche’s new system, or others like it will send the wrong message to both manufacturers and the public.

However, the argument of Peugeot is that this flywheel based system will not be suitable for road cars, is expensive to maintain and the high revving flywheel could create it’s own safety problems.

It’s a hard call for the ACO who are faced with the choice of trying to encourage new technology but also keeping it’s race affordable and relevant to it’s current teams.

Either way we know that whatever happens the battle for the greatest race will continue to attract true enthusiasts the world over like no other event in the motorsport universe.