BMW 520d EfficientDynamics

Losing its title as the most efficient saloon on the market has done little to dent the appeal of the EfficientDynamics, and the 520d remains our fleet favourite. It’s comfortable and efficient, plus the rear-drive chassis ensures that it is still fun to drive. Excellent residuals and cheap fixed-price servicing are the icing on the cake, but the Mercedes could be back to challenge it again when the facelift arrives.

When it comes to combining efficiency and desirability, few firms can rival BMW. Thanks to its EfficientDynamics tech, it makes some of the most eco-friendly models you can buy – and the 520d ED is no exception.

Based on the standard 520d, it boasts a number of mechanical and aerodynamic tweaks that reduce CO2 emissions to only 119g/km and promise 62.8mpg. And while these figures aren’t quite as eye-catching as the Mercedes’, the 5 Series doesn’t have a hi-tech hybrid powertrain like its rival.

However, the BMW does share the E-Class’s low-key styling approach. It’s more handsome and better proportioned than its rival here, yet has none of the head-turning appeal of the Audi A6 or Jaguar XF. The 5 Series in our pictures is a racy M Sport, but our standard ED test car made do with small 17-inch alloys and a much less aggressive front and rear bumper design.

Still, any disappointment with the exterior is banished when you climb aboard. The thoughtfully designed, wraparound dash is simple to use, while the low-slung driving position is spot-on. Factor in first-rate build and top-notch materials, and the BMW’s cabin feels a cut above the Merc’s. It’s well equipped, too, with leather trim, Bluetooth and dual-zone climate control all featuring.

Rear occupants get more head and legroom than in the E-Class, while the well shaped boot swallows 520 litres of luggage. And unlike the E300, there’s the option of a £390 split-fold seat, which helps give the BMW extra versatility.

The 520d ED also has the upper hand for comfort and refinement. Wind and road noise are well suppressed, and bumps that send a shudder through the Mercedes’ cabin are shrugged off. Quick and accurate steering, excellent body control and a beautifully balanced rear-wheel-drive chassis also make the 520d more fun to drive.

On paper, the 520d ED should be easily overpowered by the Mercedes at the track. Yet while the BMW’s 181bhp 2.0-litre diesel lacks the E-Class’s hybrid muscle, it still completed 0-60mph in a respectable 8.4 seconds. In the real world the torquey BMW feels nearly as fast as its rival, although its gruff powerplant isn’t as quiet as the diesel/electric set-up. However, it’s performance at the pumps that matter most in this test – and this is where the BMW’s charge for victory hits a hurdle.

The Performance Drive control’s EcoPro mode softens the throttle response and sets functions such as the climate control to a more efficient setting. However, even with this clever kit and standard stop-start, the 5 Series could manage only 39.2mpg. And while the £30,435 BMW undercuts the Merc on price, its higher CO2 emissions mean company car users will pay more in tax.

Are the BMW’s superior driving experience, classier cabin and greater practicality worth the extra monthly expense?