1991 Mazda HR-X Concept

This spirit of lightweight design delivering driving fun and efficiency, was also at the heart of the development of the rotary engine. What could be better than an ultra-compact and smooth engine with an inherently high power-to-weight ratio? Mazda saw the potential of the Wankel rotary engine early on, not only for enhancing the driving experience but also to clearly differentiate the company from its competitors. What's more, Mazda was the only carmaker to succeed commercially with the rotary engine, producing almost 2 million vehicles powered by one. For obvious reasons, the high-revving powerplants were most popular in sports cars like the iconic Mazda RX-7, the best-selling rotary model in history.

And while the rotary had its shortcomings when it came to ultimate fuel consumption, the combustion chamber set-up makes it remarkably well suited to alternative fuels such as hydrogen, which solves the rotary's petrol emission problems. The carmaker first demonstrated this with the Mazda HR-X, a 1991 concept with a hydrogen-powered twin-rotor engine mounted in front of the rear wheels, and then in 1995 with the Capella Cargo, a Mazda 626 wagon tested on public roads in Japan. It even swapped a hydrogen rotary into a first-generation Mazda MX-5 prototype.

The Mazda RX-8 Hydrogen RE unveiled at the 2003 Tokyo Motor Show would go on sale in Japan through a commercial leasing programme. Its bi-fuel rotary powertrain, which could run on hydrogen or petrol, would also see use in the similarly leased Mazda Premacy Hydrogen RE Hybrid. Featuring a mild hybrid system, it had more power and range than the RX-8. The compact MPV, known in Europe as the Mazda5, would later get a plug-in battery-electric powertrain and a hydrogen rotary range extender. Then, in 2013, Mazda introduced a prototype version of the Mazda2 EV, a limited-production battery-electric supermini with a small 330cm3 single-rotor range extender that could double the battery range while running on petrol, propane or butane.

Source - Mazda

Mazda's first hydrogen-powered concept car was the HR-X shown in 1991 at the Tokyo Motor Show. The two-rotor Wankel engine delivered 100 horsepower and was fed by hydrogen that was stored in a metal hydride tank. It had a range of approximately 120 miles and was backed by a four-speed automatic transmission. An Active Torque Control System (ACTS) was used to recover braking energy that was reused to improve acceleration and fuel economy.

The bubbly, aerodynamic vehicle had a very large windshield and exotic gullwing doors. The environmentally friendly vehicle was built using plastic and designed to be nearly completely recyclable.

By Daniel Vaughan | Jul 2020