Every car company faces environmental pressure, but not many have responded with the splendidly single-minded determination of Subaru.

Because when the new Impreza is unveiled at Frankfurt’s motor show in September, its brand-spanking, flat-four diesel engine will be a key feature, yet Subaru expects to make not a penny of profit from this much-needed new technology. Hard to believe, I know, but a senior executive at Subaru’s UK importer confided this fascinating snippet, apparently repeating what an exec in Japan said.

Maybe that comment was in jest, but with diesels taking about half of the European market and, in some countries and market segments, a much bigger proportion, it poses questions for Subaru’s long-term well-being.

Of course every car enthusiast can only applaud Subaru’s determination to go-it alone with the flat-four diesel, whose unique layout means that it can’t be sold or shared with any other car-maker.

Reputedly the design has been in development for 25 years, some of that time featuring the help of Toyota, and we know a few details, like the clever packaging of the intercooler below the engine that means it won’t force Subaru to spoil the bonnet line of the Impreza with a 1970s-era air intake. It also sits lower in the engine bay than today’s Impreza, which bodes well for road-holding, handling and turn-in.