Holy Grails don’t come often. One that could stretch the useful life of internal combustion by decades is revealed by Mazda. But its announcement is so circumscribed by environmental doublespeak I am not sure whether to believe it or not.

Mazda’s engine technology is scarcely mainstream. Persistence with the Wankel looked eccentric - if that is not an engineering inexactitude. Mazda’s research and development budget is dwarfed by those of Daimler or General Motors. Engineers have been working for years on an engine that combines the virtues of diesel and petrol. If Mazda really does put the world’s first compression-ignition petrol engine on sale in 2019 phasing all such out might not be necessary.

In January 1990 Prof Dr Ulrich Seiffert described to me a Volkswagen research engine as smooth-running as a petrol and as economical as a diesel. Head of VW research, he said computerised engine management, still something of a novelty, gave it a low level of CO2 in the exhaust. Greens at the 1989 Frankfurt Motor Show had been delighted and I wrote in The Sunday Times: “Developments like these are needed to rid the diesel of toxic emissions, because while it does not produce the same smog-provoking chemistry as the petrol engine, its output of polyaromatic hydrocarbons is toxic, and probably carcinogenic. The problem is made worse by the particulates (soot) diesels emit, for which a special ceramic chamber is needed to burn off their toxic elements. Only once diesels are equipped with this, and improvements to diesel fuel make exhaust filters work better, diesels could become the universal car engine of the future.”

In the long run diesels never were so comprehensively developed. But politicians believed lobbyists and recommended them anyway.

If Mazda’s petrol/diesel is as smooth-running as Seiffert claimed his research engine was 30 years ago, it could change politicians and lobbyists’ minds yet again. It might need spark plugs when it’s cold and one awaits a demonstration, but why does Mazda say that it has no plans to sell the technology elsewhere? The world’s car makers would beat a path to its Japanese door to buy the secret. With fuel economy to match a diesel and no high emissions of nitrogen oxides or soot, its significance would be enormous.

You would hardly guess at such a breakthrough from Mazda Europe Leverkusen’s muddled “Sustainable Zoom-Zoom 2030” press release. “A new long-term vision for technology development that looks ahead to 2030. Mazda believes its mission is to bring about a beautiful earth and to enrich people’s lives as well as society. The company will continue to seek ways to inspire people through the value found in cars.”

A Holy Grail or a press ploy for greenies? “We think it is an imperative and fundamental job for us to pursue the ideal internal combustion engine,” Mazda Research and Development head Kiyoshi Fujiwara told Automotive News. “Electrification is necessary but the internal combustion engine should come first.”

Let’s see. Mazda has a long wish-list:

Through conservation initiatives, create a sustainable future in which people and cars coexist with a bountiful, beautiful earth.
Expand measures for carbon dioxide reduction from a “well-to-wheel” perspective, considering emissions over the vehicle’s entire life cycle.
Aim to reduce corporate average “well-to-wheel” carbon dioxide emissions to 50 percent of 2010 levels by 2030, and achieve a 90-percent reduction by 2050.
Achieve this with a policy prioritizing efficiency improvements and measures for cleaner emissions that apply in the real world.
In line with this policy, continue efforts to perfect the internal combustion engine, which will help power the majority of cars worldwide for many years to come and can therefore make the greatest contribution to reducing carbon dioxide emissions, and combine the results with effective electrification technologies.
From 2019, start introducing electric vehicles and other electric drive technologies in regions that use a high ratio of clean energy for power generation or restrict certain vehicles to reduce air pollution.