Road Test: BMW 3 Series 320d EfficientDynamics 4dr

Industrial espionage must occur. This being so, other car makers should send henchmen to BMW's headquarters and kidnap the brains behind this 3-Series, then extract his wisdom. The man is a wizard.

This is the Efficient Dynamics version of the 320, and while that sounds tediously Germanic, it's also deeply impressive. Consider this: 10 years ago a 320d managed 50mpg and 152g/km CO2, figures that impressed at the time and would still beat some rivals today. A decade on, this one manages 69mpg and 109g/km, making it the first PremiumExecMobile to duck below the magic threshold of 110g. In fact, this is the most efficient BMW ever.

So you might reasonably expect it to be dawdly and dull. Thankfully, you'd be wrong because the most excellent thing about the ED is that it drives like a regular 3. Essentially this is a lightly de-tuned 320d with 163bhp - 20 less than the standard engine - though torque remains the same at a pleasingly twisty 280lb ft.

How has BMW done it? It's complicated, but basically through many and varied subtle bits of engineering. The most fantastic of which is a Centrifugal Pendulum Vibration Absorber that allows you to pootle around in a high gear at, say, 900rpm, without the engine juddering like a tumble-dryer on full chat. So you can use fewer revs and therefore consume less fuel. This pendulous magic helps the ED feel more refined than the engine on which it's based, and most other 2.0 litre-ish diesels currently on sale.

Other tech includes regenerative brakes, stop-start, lowered suspension and aerodynamic alloys to reduce air resistance, while the electric power steering, oil pump and aircon compressor are switched off when not needed. Which saves fuel. And along with the rest of the 3 range, the ED has also been facelifted, but only anoraks would spot the new bumpers and headlights, bigger kidney-shaped grille and more shapely sills.

At £27k, the ED is not a cheap way to eco bliss, but remember, this is a well equipped 3-Series. Importantly, it's priced exactly the same as a 320d SE and costs nothing to tax for the first 12 months, and just 20 quid a year after that - good news for anyone with a basic grasp of finance. All of which leaves you free to enjoy prestigey BMW-ness with added refinement and a happier wallet. And an appreciation for Centrifugal Pendulum Vibration Absorbers.