Green engine technology that can improve fuel economy and carbon dioxide emissions by over 15 per cent is coming to Britain’s favourite sports saloon, the BMW 3-series, this autumn.All the four-cylinder diesel and petrol engines sold by BMW are due to be fitted with BMW’s ‘Efficient Dynamics’ technology, a suite of engine add-ons and equipment upgrades that some car-makers refer to as ‘mild hybrids’.The important feature is that these technologies further improve the internal combustion engine without the drawbacks suffered by other green technologies.Four of the ‘Efficient Dynamics’ technologies — an integrated starter motor/alternator, computerised alternator control, auto stop/start and electronic power steering — have had stunning effects on BMW’s 1.8-litre diesel, just launched in the new 118d.The most fuel-efficient BMW-ever makes 17 per cent more power (143bhp) than the old 1.8d, but with combined fuel economy improved to an astonishing 60mpg from 50mpg, while CO2 drops to a near-hybrid level of 123g/km.That’s better than many petrol-engined superminis and not far behind those with diesel engines. This technology is also available on the 2.0d, the key engine in the 3-series range.If the 15 per cent cut in CO2 and 16 per cent reduction in fuel economy in the 1-series are carried over to the 320d, it will rate 57mpg in the combined cycle (up from 50mpg) and just 132g/km of CO2.For company car drivers those are figures that will cut the cost of motoring by reducing ved and benefit-in-kind taxes.BMW’s six-cylinder petrol and diesel models are expected to benefit ultimately, too, although at this stage they only have some of the technologies. The petrol-engined 530i, for example, only has the integrated starter motor/alternator.Test drives of the technology demonstrate a highly significant feature — that they are all but invisible to the driver.The most noticeable is the stop/start, which cuts out/in at 2mph when the clutch is depressed in neutral. But it is not obtrusive, like other attempts.As the alternator cuts in/out on the 530i, a slight whistling noise can be heard, although in the noisier 118d that’s inaudible.Despite featuring only some of the ‘Efficient Dynamics’ tech, the manual transmission 530i is now rated at 176g/km, comparable with competitor’s diesel models.
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