The fatal flaw in mythical Mercedes T 80 land speed record car

It was meant to be the pinnacle of Germany’s racing dominance. A Silver Arrow that really was quicker than anything else on the planet.

With an engine from a Messerschmitt, Ferdinand Porsche-designed bodywork honed in a wind tunnel, and Hans Stuck behind its leather steering wheel, the Mercedes T 80 was poised to wrest the land speed record from Britain: the crowning jewel for the Third Reich’s propaganda strategy.

Its target was 375mph, but the record attempt — on a stretch of autobahn — was never made, as war broke out during the car’s final year of testing. The potential of this ultimate Stromliner would remain a mystery — until now.

New analysis, to be broadcast this Sunday by Channel 4, reveals that the T 80 would almost certainly have been capable of hitting the target, in a coup for Hitler over the traditional land speed record powerhouses in France, Belgium and Britain.

However, it also reveals that the car carried a flaw, which could easily have proved fatal during the attempt to beat Surrey-born John Cobb’s mile record of 367.9mph.

CFD modelling of the T 80 was commissioned by the production team behind Hitler’s Supercars, a documentary that charts Germany’s motor sport propaganda campaign in the 1930s.

Using images and designs of the car, and conservative assumptions of its power, Silverstone-based TotalSim found that it could well have reached 400mph, helped by the low rolling resistance of the autobahn surface — compared with the Bonneville Salt Flats used by Cobb.

But lift at the front combined with downforce at the back, behind the rear axle, would have risked the car flipping during the attempt — an outcome the modern Mercedes outfit knows all too well after bringing its CLR to Le Mans in 1999.

“This car is the absolute apex of where everything was before the war,” says Jim Wiseman, director of Hitler’s Supercars. “They were using windtunnels to get these speeds. They had the manpower, the inventive engineers.

“It was also Hitler’s project, with his pet driver, his pet designer, who had developed the People’s Car, and his pet company.

“The fact that it didn’t run has given it a mythical status — would it have broken the record or not? From the figures we’ve done, I think it would.”

Wiseman says that the T 80’s instability came about because engineers had accidentally invented the rear diffuser, which increased downforce behind the rear axle, creating a significant imbalance.

The 8.2-metre machine accommodated a DB 603 V12 aircraft engine, developed for aircraft including the Messerschmitt Me 309 and Me 410. Mercedes says that the power output of the fuel-injected engine could have been as high as 3,550bhp when used with a special blend of fuel containing methanol and nitrobenzole.

Wrapped around it was a spaceframe weighing just 124.5kg, with two axles and four 1.17m diameter wheels at the back, covered in steel bodywork, that had been shaped in a wind tunnel, with side fins for downforce.

Mercedes had hoped to run the car in the autumn of 1940 but, as the year rolled on and war intensified, the engine was returned to the Luftwaffe, as the Nazi regime became more focused on the skies above Britain than records set on the ground.

The T 80’s bodywork is now displayed in the Mercedes-Benz museum in Stuttgart, its lines still other-worldly, more than 80 years after its creation.