IN THIS FEATURE Cleaning up the motor industry Injecting some sense into engines Less-polluting petrols One cylinder at a time Electric avenue Alt.fuels The regional response

Direct-injection and common-rail diesel systems are now the industry norm - for passenger cars, at least - and the new generation engines feature ever-more precise and accurate injection of fuel into the cylinders. The Volkswagen Group, for example, has vaunted its Pumpe-Duse, or unit-injection, engines, which are powerful and economical, but is now moving towards a technology called piezo-injection: this involves an electric current being passed through a stack of ceramic elements, which expand to shoot fuel into the cylinders, instead of the traditional magnetically-charged solenoids. Piezo-injection engines are currently offered in the newest Volkswagen and Audi models, and just as direct-injection TDI and unit-injection PD engines became more widely available, they should filter into more Volkswagen, Audi, Seat and Skoda models in the future and the technology will become much more widely available.

Toyota's D-CAT diesel system has been praised for its low compression ration

Piezo-injection will also feature in the Toyota/Lexus D-4D Clean Power diesel engine, along with Toyota's D-CAT catalyst system. This engine, for launch in 2006, will have the lowest-yet compression ratio of any production diesel engine, and Toyota promises market-leading low levels of emissions such as nitrogen oxide and particulates as well as excellent fuel consumption, low carbon dioxide output and good refinement. Technology such as this, combined with sophisticated engine management and throttle control systems, backs up the claims of companies such as Volkswagen who believe that, contrary to the popular image that diesel is dirty, diesel fuel has a long-term future as an eco-friendly fuel, especially since it can be derived from sustainable, organic sources (more on this below). And even in less high-tech engines, emissions can be cleaned up by the fitment of particulate traps or filters: although these are by no means widely available, they now demand no maintenance during the projected lifespan of the car, and are offered in an increasing number of mainstream diesel models. There have been calls to make them compulsory-fit on vehicles which do not otherwise meet acceptable emissions standards, as a quick-fix solution.