Punchy, refined and ever so frugal, BMW’s latest diesel engine provides the 520d with a new lease of life
16 September 2014

What is it?

A slightly faster, more economical and further refined version of one of the UK’s best-selling executive class estates – the BMW 520d Touring.

Having undergone a mid-life facelift last year with a number of mild exterior and interior styling tweaks, Munich’s popular mid-range model has now received a new four-cylinder diesel engine in a move that further enhances its standing against rivals including the newly facelifted Audi A6 2.0 TDI, Jaguar XF 2.2D and Mercedes-Benz E220 Bluetec.

The B48-designated unit is the same longitudinally mounted 2.0-litre common rail unit unveiled in the facelifted X3 xDrive20d back in April. In the 520d, it delivers 187bhp at 4000rpm and 295lb ft of torque on a band of revs between 1750 and 2500rpm.

This gives it a slight 6bhp and 15lb ft increase over the old N47 engine, with which the 520d’s new engine shares its 90.0mm bore and 84.0mm stroke measurements. Despite the apparent similarities, though, BMW claims the B48 is new from the ground up.

Key among its developments is a new Bosch injection system. It operates at a higher pressure than previous incarnations, reaching peak values of up to 2000bar or some 200bar higher than before. It also receives injector nozzles with seven holes for improved combustion properties.

The new BMW engine also adopts a new variable geometry Honeywell turbocharger that is claimed to bring a 50 per cent reduction in frictional losses due to new bearings. There is also a more efficient electrically operated oil pump that brings reduced pumping losses compared with the older N47 engine.

As before, buyers can mate the 520d’s new engine to a standard six-speed manual or optional eight speed automatic gearbox – the latter running a heavily over driven 0.64:1 top gear in combination with a 3.1:1 final drive ratio and a range of fuel saving features that underpin BMW’s EffientDyanmics initiative.

Alongside standard rear-wheel drive, BMW also offers the 520d with optional xDrive four-wheel drive. Beware, though. Despite its traction enhancing qualities, it adds 105kg to 1735kg kerb weight of the standard rear-wheel drive 520d Touring driven here, taking it to 1840kg.


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For those on a tighter budget, BMW has also launched a reworked version of the 518d in both saloon and Touring bodystyles. It receives a slightly detuned version of the B47 engine with 148bhp at 4000rp and 265lb ft between 1750 and 2500rpm.  

What's it like?

With the efficiency advances made by four-cylinder direct injection petrol engines, the venerable common rail diesel has come under increasing sales pressure of late. But in the case of the 5-series it is the four-cylinder oilburner that continues to rule the roost, accounting for up to 20 per cent of sales on a global basis.

In its latest incarnation, BMW’s four-cylinder diesel engine proves highly convincing, providing the 520d with a broad spread of performance, outstanding efficiency and improved refinement.

The adoption of a new injection process and alterations to the induction process sees the B47 deliver more instantaneous response and even greater mid-range flexibility than the old N47 engine.

It is only low down in the range that the new 2.0-litre unit struggles with its relative lack of capacity, offering acceptable but far from strapping qualities below 1500rpm. From there onwards there is strong urge until the efforts of the engine begin to tail off beyond 4500rpm. 

Perhaps more than the additional power and torque, it is the improvement in cold start and on-boost refinement that really marks the 520d’s engine out.

With improved frictional qualities and additional sound deadening material in the form of a plastic jacket that nestles around the new engine to dampen mechanical noise, it offers truly hushed qualities at typical motorway speeds. It is only when you explore the upper reaches of the rev range that you begin to register any traditional diesel like acoustics – and even then it is hardly loud. 

The ultra-precise shift action of the optional eight-speed automatic gearbox, as fitted to our test car, adds to the impression of outstanding refinement, providing crisp and intuitive shifting in any situation.

In kick down mode, it will drop up to four gears to provide the 520d Touring with convincing vigour on the run. A heavily over driven 0.64:1 eighth gear ratio and 3.08:1 final drive also endows it with a wonderful loping gait at typical motorway speeds thanks to the strong levels of torque.

In saloon guise, the new 520d is claimed to hit 62mph in 7.7sec and reach a top speed of 145mph. But with an added 135kg, the Touring requires just less than 8.0sec and runs to 140mph. However, it is at the pumps where the new BMW really impresses.

Official economy claims give the 520d saloon a combined 69.0mpg and average CO2 emissions of just 109g/km in combination with standard 17-inch wheels and 225/55 R17 tyres. The 520d Touring can’t quite match it, but its 62.8mpg and 118g/km is still very impressive, endowing it with a theoretical range of 967 miles on the car’s standard 70 litre fuel tank.

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Criticisms? The interior of the sixth-generation 5-series is beginning to show signs of age with some less than dazzling materials and a clutter of buttons spread across the dashboard.

The optional adaptive damping control system is also unnecessarily complex, offering five different modes: Sport Plus, Sport, Comfort, Comfort Plus and Eco Pro. Choice is good but one has to ask: do you really need such finite adjustment?

Should I buy one?

Along with the charms of its new engine, the 520d is also an engaging drive when set up in Sport Plus mode – where its instruments alter from a cool shade of white to a glaring shade of red.

If you’re in the market for an executive class car or are looking at securing a new company car you’d be mad not to give it consideration. As far as every day motoring goes, it is about as much as you’ll ever need, not least in Touring guise. 

BMW 520d Touring automatic

Price £35,840; Top speed over 140mph; 0-62mph under 8.0sec; Economy 62.8mpg; CO2 118g/km; Kerb weight 1735kg; Engine 4-cyls, 1995cc, turbocharged, diesel; Power 187bhp at 4000rpm; Torque 295lb ft at 1750-2500rpm; Gearbox 8-speed automatic

16 September 2014
Its a shame because it actually needs a sixth option : Automatic.
Also I presume where they state the fuel economy for the touring it is for the 4wd variant as driven, so the actuall difference with the saloon would be a lot less for the 2wd version.

This engine, gearbox and 4wd in a 2 series please.

16 September 2014
audiolab wrote:

Also I presume where they state the fuel economy for the touring it is for the 4wd variant as driven, so the actuall difference with the saloon would be a lot less for the 2wd version

No - it is the figure for 2wd - I have been looking keenly at this and when announced a few weeks ago just under 120 was the figure given for the SE auto touring sdrive, not 4wd (which is not available in UK)

16 September 2014
will be interesting to see if it can achieve 62.8mpg ,doubt it somehow,it will be nearer to 40 -45mpg.


16 September 2014
...the real world fuel consumption figures, given the disrepute into which official figures have fallen. Interesting to see the 535d (lesser diseasels are not available Stateside) fuel economy figures: on the BMW USA site it's listed as 38mpg highway. Adjusted for US/Imp gallons this equates to 45.5mpg over here. BMW UK quotes an extra-urban figure of 55.4mpg. For city/urban the US figure is 26 (31.3 adjusted), in the UK the quoted figure is 42.2mpg. So, I'd knock around 25% off the (combined) BMW/EU figures for the '20d - so yes, around 45mpg.

16 September 2014
Unfortunately, I cannot understand such a succes for this kind of engine in a big BMW. Definitely not the ultimate driving machine.

16 September 2014
Whether it is realistic or not is somewhat irrelevant, it is a standardised test that is equal to one and all. It is highly unlikely that many will adhere to the conditions in the test and are therefor highly unlikely to achieve such figures. Anyone that expects to achieve such figures under real world use is only fooling themselves. I agree the older constant speed figures were more useful and would welcome their return (but that would scare Range Rover etc users).

A full tank of fuel, partners, children, junk in the boot, roof rack, bike rack, any speed over 55mph,this , that and lots of the other. Each will take their toll on any stated figure, put a few together and you don't stand a chance. It is a statement of what can be acheived. I do not doubt that manufacturers do all they can to make these figures the best they can etc etc. I regularly match and ocassionally exceed my stated fuel economy figures, I drive like an old fart but it gets me 64 - 70 mpg and thats brimmed tank readings not one off journeys (seat ibiza st 1.6tdi). Yeah yeah, I know bully for me, but it can be done.

16 September 2014
...of a similar unit in the Audi A6. In that, economy was an easy 50-52 mpg with more available if you were careful. Given that this 5 Series has lower CO2 than the Audi I'd expect at least the same in give and take driving.

16 September 2014
What is it with BMW and Diesels?,just about every BMW you see driving along is a Diesel!,what's wrong with a Petrol one?!

16 September 2014
Dear Peter,
I was just complaining about a 4pot diesel in such a beautifull car. I definitely cannot understand this way of driving...

16 September 2014
Peter Cavellini wrote:

What is it with BMW and Diesels?,just about every BMW you see driving along is a Diesel!,what's wrong with a Petrol one?!

Because they are all leased company cars


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