Mazda RX-500: A Futuristic Rotary Showcase
Over the course of the 1960s, Mazda invested a large amount of resources in attempting to further the development of its Wankel rotary engines. The first Mazda production car to be fitted with an engine of this style was the Cosmo 110S in 1967, which saw the beginning of Mazda’s famous and lengthy rotary history. As with any new technology, Mazda had to try and prove the worth of the Wankel engine. Initially this was through motorsport, with a pair of Cosmos entered in the 1968 Marathon de la Route: a staggering 84-hour endurance race at the Nürburgring. A fourth-place finish for one car certainly aided the reputation of the new technology, with the other car retiring due to a mechanical fault not related to the engine.
The cars entered into the Marathon de la Route were largely standard, with only limited modifications made for racing
Following this, Mazda began development of a concept car intended to draw yet more attention to its rotary engine, while also marking the 50th anniversary of the founding of the company. Debuting at the 17th Tokyo Motor Show in 1970, the Mazda RX-500 was essentially the ultimate sports car that Mazda’s designers could come up with at the time. To coincide with the idea of the Wankel engine being cutting-edge, the RX-500’s styling was suitably futuristic. The breadvan-style body was chosen in the pursuit of effective aerodynamics, though a more traditional coupe and racing version were considered early in the design stage.
Powering the RX-500 was a variant of the 10A two-rotor Wankel engine, based upon the versions used in Mazda’s race cars at the time. The 982cc engine (491cc per chamber) was mid-mounted, with power being sent to the rear wheels through a four-speed manual transmission taken from a Mazda Luce Rotary Coupe. In this spec, the 10A reportedly produced 247hp and reached a redline in the region of 15,000rpm, which is incredibly high even by rotary standards. According to Mazda at the time, the RX-500 achieved a top speed in excess of 150mph at the company’s test track.
Not only did the RX-500 have impressive performance numbers, it also weighed in at only 850kg. This was largely thanks to the widespread use of plastic-based body panels throughout the design, which was the first time Mazda had experimented with this style of bodywork. Another piece of cutting-edge technology fitted to the RX-500 was the brake setup: ventilated disc brakes in both the front and rear had previously only really been seen on race cars. The RX-500 featured butterfly doors to add to its exotic appearance, while also including a gull-wing door setup for accessing the engine compartment, much like the De Tomaso Mangusta of the same era.
However, the doors were not the most distinctive styling element of the RX-500. That honour goes to the taillight setup, as odd as that may sound. Along with its other purposes, the RX-500 was intended as a ‘test bed for high-speed safety’, and as such featured some unique lighting. Rather than a traditional taillight cluster, the rear of the RX-500 had curved towers of lights on each side of the car. At the top there were green lights, which would turn on when the car was accelerating. Beneath these there were amber lights, which were activated when the RX-500 was maintaining a consistent speed. Positioned under these were the regular red brake lights, with the intensity of the brake lights being affected by how much brake pressure was applied.
Following the conclusion of its use as a display car, the RX-500 was placed in storage in a Mazda facility and largely forgotten about. In 2008, around 30 years since its last public appearance, the car re-emerged. It underwent a full restoration, and it is now a permanent display exhibit at the Hiroshima City Transportation Museum. Up until the restoration, it was believed that Mazda had built three separate RX-500s for its various display appearances: one green, one yellow, and one silver. However, when a damaged door was being repaired it was discovered that there were three layers of paint on the panel: a green layer, a yellow layer and the top silver layer. Mazda had simply tweaked the bodywork slightly and resprayed the car for each appearance, to give the illusion of multiple examples being produced.
The RX-500 was briefly shipped to the UK for the 2014 Goodwood Festival of Speed, where it was a star attraction. It was a stationary exhibit, as it is in its permanent home, because while the car does still run, it isn’t to the same standard that it once did. While this does mean it won’t be reaching that supposed 150mph top speed any time soon, it is nice that Mazda has continued to display the RX-500 for the public to see nearly 50 years on from its debut.