In an era when car rollovers often meant a death sentence, Mercier found a way to defy fate. He introduced his "acrobatic car" to the public, demonstrating its ability to perform multiple rolls before returning to an upright position, leaving the driver unharmed.

Little information exists about Mercier, other than his origins in Paris or Maubeuge, France. The only known record is a small article in the January 1927 issue of Popular Science Monthly about Mercier and his acrobatic car. The article described the vehicle as essentially a "5-horsepower European car".

Mercier's invention, however, did not gain widespread adoption. It was not until nearly 40 years later that British racer John Aley pioneered the development of the roll bar.

In 1963, after Aley experienced and witnessed several near-fatal rollovers in competitions, he commissioned fabricator Brian Wilkinson to create a three-point roll bar for his car. Aley then commercialized it, naming it the Aley Bar. Wilkinson, in turn, founded Safety Devices, a manufacturer of roll cages.

By My Anh (via Mac's Motor City Garage)