Is the BMW 320D Efficient as good as it looks?

This BMW 320d Efficient Dynamics is the cleanest, greenest, most fuel-efficient 3-series ever. It’s designed to appeal to fleet buyers and the environmentally conscious alike, and thanks to some further tuning and tweaking of the company’s biggest selling Three, the 320d Efficient Dynamics will, on paper at least, achieve 68.9mpg and emit a remarkable 109g/km.

So this is a BMW 320d Efficient Dynamics? But I thought Efficient Dynamics was standard?

It is – since BMW first revealed its eco-friendly Efficient Dynamics technology in 2007, every manual 320d that’s emerged from Munich’s factories has been fitted with active aero, low-rolling resistance tyres, a gearshift indicator, an intelligent alternator and a stop/start system

But there’s now a new version. So far the Efficient Dynamics tech has all been standard and relatively under-the-radar (whereas Mercedes badges all its latest models Blue Efficiency) but BMW has now come up with an even cleaner 3-series. It’s the company’s special eco model, with extra tweaks to make it even greener and save you money with its startling CO2 output.

So what are the important changes?

The four-cylinder diesel is the familiar single-turbo 2.0-litre unit that powers that 316d, 318d and 320d, but some engine tweaks lower the power (and thus the CO2 output), but the torque output is actually up. The usual complement of Efficient Dynamics tech is standard, but this 320d has a longer final drive ratio, new 16-inch ‘Aero’ alloys and lower suspension.

Beyond that there’s a new two-mass flywheel with a centrifugal-force pendulum – it sounds complicated but effectively weights inside the flywheel counteract the vibrations from the engine. In itself this doesn’t improve emissions but the system is claimed to make the driving experience smoother at lower rpm, which should in turn encourage drivers to use fewer revs and higher gears. And that’s means more miles per gallon.

But the end result isn’t an efficient-but-achingly-slow BMW. After all the tweaking this 320d puts out 161bhp and 265lb ft, respectively down and up on the regular 177bhp/258lb ft 320d. Plus the on-paper performance differences are marginal – the new car is three-tenths slower to 62mph (at 8.2sec) and three digits slower flat out (as if it matters).

The emissions and economy figures are even more impressive – the 320d ED manages 68.9mpg on the combined cycle and only emits 109g/km, compared to 58.9mpg and 128g/km for the normal car. Buy a 316d and you’ll still only managed 62.8mpg and 118g/km. That means the 320d Efficient Dynamics driver will only pay £35 a year in tax, and face a meagre 13% benefit-in-kind. So the UK is expected to take around 60% of production, and it should account for 30-50% of 320d sales in Blighty, whether it is BMW 320D personal leasing or simply buying it outright- the BMW efficient dynamics is expected a bright future.