The Mazda RX500 Anomaly

The extremely rare and fully functional Mazda RX500 concept car was unveiled to the general public at the 17^th Tokyo Motor Show in October 1970 where the theme was low emissions, fuel efficiency, safety and compact city commuter cars. Buoyed by the success of just hosting the World’s Fair in Osaka, European manufacturers were invited to participate for the first time. Unfortunately, this allowed Mercedes Benz to display its truly ground breaking C111 that had debuted just a year earlier at Frankfurt, a car that featured a 4 rotor engine. The design of the RX500 was embarrassingly similar to the C111 and its execution was diminutive in several regards. Perhaps this is why the car has remained hidden for so many decades until its recent factory restoration in 2008. It is confusing what the Mazda executives were pondering with its creation. As a follow up rotary powered prototype to the fabulous Cosmo Sport that was shown in 1964, this car was too extreme to ever see production and reflects approaches that the company never revisited in the following decades. It was indeed a strange beast.

RX500 at the Tokyo Auto Show in 1970.

Click these images for full screen view.

Mazda began Project X810 in 1968 so they can be absolved of pilfering ideas from the C111. Mazda wanted to research the driving dynamics of fiberglass bodied vehicles in excess of 125 mph as well as develop a potential successor to the Cosmo Sport. Designer Shigenori Fukuda determined that the additional roofline length of a wagon style body (Estate or Shooting Brake) along with a Kamm style rear end was more aerodynamic that a coupe. He was apparently inspired by Kubrick’s 2001: A Space Odyssey and the design elements of the interior, the scissor doors, the gull wing doors over the rear midengine compartment, and the hidden A pillars which give the look of a one piece wraparound glass canopy reflect that focus.

Rx500Interior — The Green and Orange leather interior is a prescient nod to the iconic Renown livery on the Mazda 787B which won the 1991 *24 Hours of Le Mans*. Three dials adorn the instrument bin with the leftmost indicating the tuned frequency of the AM/FM radio and the right dial showing a tachometer redlining at 15,000 rpm! The 4 speed manual transmission is sourced from the 1969 Luce R130 Rotary Coupe.

And don’t forget the psychedelically lit rear with green lights at the top indicating acceleration, yellow lights just below indicating constant speed and a series of red brake lights proportionally lit to the degree of braking effort used. This was the safety design aspect of the auto show. Notice also the effort expended on heat dissipation which is a chronic issue with rotary engines, namely the screened ventilation portals and the open back of the engine compartment. Finned heat sinks have also never been seen again on factory Mazda exhaust systems.

Rx500mirror — The vents in the side view mirrors are designed to vent fresh air into the passenger compartment.

RX500Engine — The engine is a peripheral ported twin rotor 10A Mazda rotary engine displacing 982 cc and producing 247 bhp @ 8000 rpm and good for nearly 150 mph. Fed by a 50mm downdraft Mikuni, the car weighed 850 kg. The lower left image shows the open front “hood” revealing a compartment housing all the electricals and a nose mounted radiator.

clay. — Clay modelling of the RX500. A 1:5 scale model was used for wind tunnel testing and a 1:2 scale mock up unveiled in January 1970, giving only precious few months to manufacture the actual running prototype.

Restore — 10A engine opened showing blown coolant seals. The RX500 had laid forgotten and under dust for decades hidden in a Mazda warehouse before the 2008 restoration.

GreenRX500Forest — The official press release photo of the RX500. The original color was lime green and it was repainted for the Tokyo Auto Show. After the show, the retractable headlights were damaged and replaced with fixed headlights and the entire car repainted in silver, as it appears today. (I suspect that had this car gone into production it would’ve with retractable headlights like the SA-Rx7 but I doubt any effort was expended to make them operational in this prototype. I have never seen a photo with the headlights in a raised position.)

The Toyo Kogyo Company was founded in 1920 so the RX500 was named to commemorate its 50th anniversary. Except then it should be known as the RX50. So much of this car remains a mystery!