BMW 520d Efficient Dynamics

The BMW 520d EfficientDynamics Edition is a fantastic addition to the range. Thanks to a few relatively minor - and invisible - tweaks, emissions have been cut to 119g/km and fuel economy is improved. That means it falls into the 13 per cent BIK bracket, which means significantly less company car tax than its rivals. Despite that it does everything else as well as a regular 520d does, so it's great fun to drive and is as luxurious as an executive car should be.   

BMW has launched its most economical 5 Series yet – the 520d EfficientDynamics Edition. If you're a company car driver, it's the BMW 5 Series you've been waiting for, as it'll cost you the least in benefit-in-kind tax compared to any of its rivals. 

Sitting in the 13 percent BIK band, it's much cheaper to run than an Audi A6 or Mercedes-Benz E-Class (both 18 per cent), while the entry-level Jaguar XF costs business users 22 per cent.

That's all down to the BMW's CO2 figure of 119g/km. Along with the low BIK rating, road tax is also very low thanks to band C VED rating, which means you'll pay nothing in the first year and £30 thereafter. 

High mileage drivers will appreciate the extra four miles or so eked out of a gallon of diesel. That's how much more economical the EfficientDynamics model is over the regular manual 520d - 62.8mpg against 58.9mpg. Small gains on the face of it, but company cars are costed on their whole life costs, not just one journey.

So how does BMW manage to pull these figures out of a big, comfy four-door executive saloon when there are plenty of superminis still on sale emitting more CO2 and using more fuel? It comes down to just a couple of items.

Along with a slick manual gearbox are ultra low rolling resistance tyres, wrapped around slippery 'Streamline' alloy wheels that help ease the passage of air flow around the car. Other than that there's nothing externally to tell the EfficientDynamics Edition apart from the regular 520d.

What you can't see is an altered final drive ratio. This has the effect of reducing engine revs on the motorway, which, unsurprisingly, leads to lower fuel consumption. The fact it makes the BMW 0.1 seconds slower to 62mph from zero is pretty irrelevant. A time of 8.2 seconds is plenty quick enough and the 520d feels as effortless as ever in the mid-range.

Peak power is unchanged, at 181bhp, while there's still the same 380Nm of torque under your right foot from 1,900- to 2,750rpm. No compromises there then.

Without a back-to-back test with a normal 520d it's impossible to say if the new tyres have any effect on the driving experience, though that statement alone illustrates that, if there are any differences, they'll be small.

As ever the 5 Series has one of the best chassis in the business, managing to be luxury-car comfortable, though agile and good to drive when the mood takes you. The new eco-measures do not detract from all that.

Drivers of the EfficientDynamics Edition can go a little further as well, as this model introduces BMW's new ECO-PRO mode to the 5 Series. It alters the engine map, throttle sensitivity and the amount of power used by the climate control, etc. to return the best possible economy.

It'll even let you set a speed at which you'd like to be reminded to reign in your exuberance in the name of fuel economy. This mode is coming to the rest of the 5 Series line-up too.