Michelin Put This Porsche 904 On Citroën Hydropneumatic Suspension And Used It To Test Tires For Many years

Porsche’s ludicrously beautiful 904 Carrera GTS is amongst the good race cars of all time. With a light-weight fiberglass body and a rev-happy gear-driven twin-cam flat-four engine, it was an actual zinger on the race track and on hillclimbs within the mid-Nineteen Sixties. I’m an absolute dork for 904s, so once I saw this automobile — chassis number 904-034 — on the Le Mans Museum back in 2014 and snapped the terrible iPhone 6 photo you see below, I was immediately intrigued by its story. This automobile has lived in my brain rent-free for over a decade, and I think I finally have the total grasp of its story — and what a story it’s!

Bradley Brownell

The automobile was originally delivered to Herbert Müller in 1964, and was raced on the 24 Hours of Le Mans amongst other events, before it was sold to world-record cyclist Roger Rivière who desired to get into racing. When Rivière eventually realized how dangerous racing was, he quickly sold the automobile. That is where the story gets interesting, because it was purchased by famed French tire manufacturer Michelin. 

Once in Michelin’s care, the automobile was immediately shifted to tire test duty at the corporate’s Ladoux test center, itself brand latest from 1963. Michelin determined that it needed a automobile which could test a whole lot of differing types and sizes of tires, including the strength of tire sidewalls under stress. As a technique to increase stress on the sidewalls, the automobile was fitted with then-new Citroën DS hydropneumatic suspension with a purpose to vary the ride height and modify the middle of mass. 

By 1967 the automobile’s original Fuhrmann twin-cam engine had been put through the paces in racing and tire testing with who knows what number of hard kilometers, and it decided to run out. Through the course of its hard three years on earth, it was damaged front and rear from crashes, and the engine was gone. Michelin set about putting the automobile right, or right enough that it could proceed testing tires. The bodywork was fixed and the automobile was painted vivid orange for safety reasons. The unique 180-horsepower four-cylinder was yanked out and put under a tarp out behind the constructing, to get replaced by a then-new 1967 Porsche 911S flat-six engine, making the identical 180 horsepower from the identical two-liter displacement. 

I’ve reached out to Michelin a number of times through the years to find out more concerning the automobile’s history, or perhaps uncover some period photographs of it in test livery, but they either don’t exist or are buried deep in the corporate archives and no one cares enough to dig. It’s not known how long the automobile was used for tire testing, or which tires it was used to check, nevertheless it seems the automobile could have seen motion on the Michelin Engineering & Services test track deep into the Nineteen Eighties before it was shelved. It was shoved right into a garage somewhere and forgotten about until 2001 when an engineer uncovered the automobile and tracked down its Le Mans history. 

This rolling laboratory had served the tire company well, and had been discarded to the depths of cold storage. The engineer, who was from Le Mans, France, reached out to the Le Mans Museum to see in the event that they is perhaps interested. Between the engineer and the museum curator they were capable of wrench the automobile, and its original blown-up engine, freed from the enormous corporation’s grasp. It was, by all measures, in seriously rough shape. 

With support from Michelin and oil company Motul, the automobile was given a full and very careful restoration back to the way it looked when it first arrived at Michelin in 1965 or ’66. That original Furhmann four-cam engine, itself now valued deep into the six figures, had cylinders filled with hazelnuts on teardown, evidence that a squirrel had made the engine its home in some unspecified time in the future between 1967 and 2001. Given a sympathetic restoration the automobile is a rolling piece of weird history, blurring the road between race automobile and road automobile technology. This thing should have been an absolute hoot to drive within the ’70s with its vivid orange paint, deep flat-six wail, and French-supplied adjustable suspension. I’m so glad it wasn’t left to rot in a warehouse somewhere, that thing belongs in a museum.