Audi has proven itself to be the dominant force in Le Mans prototype racing over the course of the past decade, but to stay on top, any team — regardless of past successes — needs to have some of the best equipment available. Audi hopes its new R18 LMP car, unveiled late last week, proves to be precisely that.

Audi’s new LMP car is still diesel-powered, but in order to comply with new FIA regulations, engineers had to dial back the displacement from the outgoing R15+. As a result, the R18 now uses a 3.7-liter turbo-diesel V-6, a far cry from the 5.5-liter TDI V-10s found in the R10, R15, and R15 Plus. Other driveline modifications include the gearbox; the R18 uses a six-speed sequential gearbox in lieu of last year’s five-cog unit.

A smaller engine does trigger a loss in power, but Audi’s team focused on ways on using every last ounce of energy packed within the R18. As a result, attention was focused on the car’s aerodynamics in order to help reduce drag and increase efficiency. Wind tunnel testing forced a number of changes, notably the enclosed cockpit — a feature we haven’t seen on Audi LMP cars since the 1999 R8C.

Overall, the R18 looks drastically different than the company’s previous LMP cars. Regulations required the new car to utilize equally-sized wheels in front and back, which in turn forced designers to add some very pronounced wheel arches. The FIA also forced Audi to adopt a large dorsal fin running along the top of the engine compartment, but the headlamps — which incorporate LED lighting and accent pipes — are certainly Audi-designed accoutrements.

The new R18 will make its competitive debut at the Spa-Francorchamps in Belgium on May 8th. Audi plans to enter no less than three R18 s for the 24 Hours of Le Mans race on June 11th and 12th. In total, the new R18 will contend in six races for the 2011 season, including the Petit Le Mans race at Road Atlanta on October 1st.