When the last Mazda RX-8 sports car rolled off the assembly line in Hiroshima, Japan last week, it was the end of the line not only for the car but for the novel rotary engine that powered it.
After 45 years of continuous production, Mazda's rotary engine experiment has come to an end. Or has it?
Some company officials have suggested that a new rotary engine might find use as a range-extender for a plug-in hybrid vehicle, along the lines of the Chevrolet Volt. But there are no known plans for such a project by Mazda at this time.
There is also some speculation that a hydrogen-fuelled rotary engine might have some future application as the rotary seems to have a particular affinity with that gaseous fuel. But it's a long shot.
When it was introduced in the early 1960s, the rotary engine (sometimes called the Wankel engine after its inventor, Felix Wankel) showed huge promise.
In concept, the Wankel comprised one or more roughly triangular rotors, each rotating in their own housing, shaped like an ellipse with a pinched mid-section.
With only a fraction of the moving parts in a piston engine, it was compact, light in weight, smooth running and capable of very high speed and high power output.
Mazda later capitalized on its smoothness with ads that focused on its mmmmm sound.
It even found use in such diverse applications as lawn mowers and snowmobiles.
Germany's NSU (later merged into Audi) and Mazda were the first automakers to put the rotary engine into production, although Mercedes-Benz gave it a look and General Motors came very close to production, terminating a multi-year development project virtually on the eve of its introduction.
Mazda's first rotary-powered production vehicle was the 1967 Cosmo coupe, a prime example of which is owned and has been restored by Mazda Canada.
The rotary's Achilles heel was the double whammy of emissions and fuel-economy regulations, which became challenges for all automakers in the early 1970s. Both were particular challenges for the rotary engine.
The rotary also had issues with oil consumption and durability, primarily as a result of premature wear on the sealing tips at the corners of the triangular rotors.
As a result, Mazda became the only automaker still producing a rotary engine, applying it to a broad range of vehicles, even including a pickup truck – although few of those ever made it to North America.
By 1978, when the RX-7 sports car was introduced, it was the only rotary-engined vehicle on sale on this continent.
The rotary engine doesn't kick you in its back with low-end torque, like a big-displacement piston engine, but it seems to wind forever, increasing power output as goes and producing almost turbine-like acceleration.
As a result, the RX-7 and its rotary-powered predecessors, were favourites of the racing fraternity and remain so to this day.
In 1991, a purpose-built Mazda 787B race car became the only rotary-powered car, and the only Japanese brand, ever to win the 24 Hours of Le Mans.
The RX-7 and its successors, including various iterations of turbocharged rotaries, culminating in the RX-8, continued to be the sole rotaries sold in North America until the RX-8 was withdrawn in 2011.
It continued to be sold in other markets – until production ceased on June 22, 2012.
To learn more about Mazda's history of rotary-engined vehicles, click here.