Voisin C6 'Laboratoire'


Contrary to what you may think, I don't own many car books. I've got a set of this one hardcover series from Italy that lists every vehicle in the world, with specs, covering most of the 1970s and a bit of the 80s.

There's some weird shit in those. (They even put the NSU Trapeze on the cover one year!)

My most prized book, other than Best Damn Garage in Town, is the evocatively-titled André Lefèbvre and the Cars He Created at Voisin and Citroën. 

I'd long known that early Citroën cars had a shared design lineage, but hadn't realized to what extent Lefèbvre had shaped the course of not only Citroën but, earlier, the great Avions Voisin marque.

Lefèbvre's well-known credits as a design engineer include:

  • Citroën Traction Avant
  • Citroën HY
  • Citroën 2CV
  • Citroën DS

How good were his designs? Those four vehicles were on sale for a combined 119 years(!) He was a character not unlike Ferdinand Porsche, Gordon Murray, or Adrian Newey, with a mind capable of designing every last nut and bolt to his specifications.

He also won the 1927 Monte Carlo Rally, invented the retractable hardtop and, in the case of today's car, introduced the world's first monocoque chassis. (You know, like how every modern passenger car is made.)

The 1923 C6 'Laboratoire' (which I'll now refer to as the C6) was created in response to an angry Automobile Club de France, organizers of the popular Grand Prix de Vitesse held in Tours. The club, after being surprised at an earlier aerodynamically-shaped Voisin dominating competition at the Grand Prix of Lyon a year earlier. 

The club published not only exact dimensions for four seat vehicles but denounced the "aerodynamic experiments" of competitors. This spurred Lefèbvre to not only write a sarcastic letter in response, but announce his entry to the Grand Prix de Vitesse in just six months.

Lefèbvre knew that Voisin's sleeve-valve engines were far behind on power, but he also knew that aerodynamics and light weight could help offset a lack of power. He was familiar with how airplanes were constructed, from his aeronautical days (oh, right, forgot to mention that he began his working career as an aircraft designer.) 

Sculpture by Philippe Guegan

Sculpture by Philippe Guegan

Built as an aluminum and ash wood monocoque chassis, the C6 had a number of novel features, including:

  • Wire mesh racing windshield (for less weight)
  • Propellor-driven water pump
  • Enclosed rear wheels
  • Lift-up tail with spare tire underneath
  • Front drum brakes
  • Magnesium pistons for the six-cylinder engine

Even though the motor made 80 horsepower, its weight of 660 kg (1455 lbs) made it the lightest car in the field—and some 30kg lighter than 2014 Formula 1 cars! With its slippery shape, the three C6 Voisins entered could hit 175 km/h (108 mph)…which wasn't fast enough.

Bugatti entered four streamlined Type 32s (known as the 'Tank' cars) that could do 180 km/h; Fiat's big supercharged 8-cylinder entry hit 195 km/h (121 mph).

The race was won by a Sunbeam; Lefèbvre was the sole Voisin to finish, fifth, covering 798 kilometres (495 miles) at an average of 105 km/h (65 mph).

Competition was not only exhausting for Lefèbvre and his team, but expensive. The small Voisin company couldn't afford to develop more advanced racing engines to compete with larger manufacturers, and so had to carefully choose where they entered. A later race at Monza, Italy, showed that the cars were far off the pace in straight-line competition.

The C6 wouldn't be the last innovative Voisin race car design, but in just a few years Lefèbvre was off to Renault—because by that point Voisin couldn't afford to make payroll—then to Citroën in 1933. 

His former employer, Voisin, was finally closed in 1939. The C6 Laboratoire? All three originals are gone. (The car above, photographed at Goodwood, is an exacting recreation.)

Sources / Recommended reading

  • Voisin C6 'Laboratoire': André Lefèbvre and the Cars He Created at Voisin and Citroën (Google Books), switchimage.org < highly recommended, with lots of awesome photography of a C6 Laboratoire recreation made in the 1990s.
  • Voisin: Wikipedia
  • André Lefèbvre: Wikipedia