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

The technology grabbing all the headlines, however, is hybrid technology: cars like the Toyota Prius - the must-have vehicle for Hollywood stars with an environmental conscience (or those seeking positive PR) - and Honda Civic IMA, Honda Insight and Ford Escape Hybrid have outsold all manufacturers' expectations. These effectively combine an efficient petrol engine with an electric motor; the electric motor propels the car silently and cleanly from start-up and at low city speeds, with the petrol engine kicking in when more acceleration is needed, and is assisted again by the electric motor when, for example, more urge is required for overtaking. The models already launched have proven themselves in terms of reliability, and the technology will be applied to more models imminently. Other manufacturers have also pledged to offer hybrids in the near future. Cynics have argued that hybrids still offer little - if any - advantage in terms of fuel consumption and cost-per-mile than a comparable diesel engine, and they are more expensive to produce and buy, but the electric 'city' mode is an undoubted plus point, and after all, Leonardo DiCaprio owns a whole fleet of Toyota Priuses... Diesel-electric hybrids promise even greater advantages, and the first production examples should appear in the near future, although these are even more expensive to produce than petrol hybrids.

Nissan's FCV uses a fuel cell to create electric power

Hybrids are still seen as a relatively short-term solution, however, as they still depend on finite-source fossil fuels, and companies such as BMW have refrained from jumping on that bandwagon. BMW has been focussing on hydrogen and fuel cells. Unlike other manufacturers, though, BMW uses hydrogen in a conventional combustion engine to convert energy directly into drive power. Other manufacturers believe fuel cells driving electric motors is the way forward: a fuel cell car basically takes hydrogen as a fuel source, uses a platinum converter to set up a chemical reaction to break it down into steam - the only by-product - and releasing electrical energy, which is stored in batteries to power electric motors. Although at the moment hydrogen is expensive to refine for fuel use, it can be extracted from water, and if it becomes widely adopted, economies of scale will make it more commercially-viable. Other companies such as General Motors are working with fuel companies to establish an infrastructure for supply and retail of hydrogen, and specialists such as Ballard are getting closer to solving problems such as on-board storage of the potentially explosive gas, which demands very high pressure containers. There are test fleets running in Europe and the US, however, and hydrogen powertrains are being fitted in a number of buses and specialist commercial and industrial vehicles - bulky storage tanks are less of an issue with such applications. Popular opinion is that hydrogen probably is the fuel of the future - but not just yet.