REVIEW DATE: 02 Jul 2009
BMW aims to prove bigger isn't always better when it comes to diesel engines. Steve Walker takes a look at the 740d.
When BMW announces that it has created its most powerful engine ever, the automotive world sits up and takes notice. There have been numerous groundbreaking high performance powerplants installed under bonnets carrying the famous blue and white roundel in the past, so any unit capable of trumping them should be special. There's a slight caveat with the engine we're looking at here in that it was merely heralded as the most powerful diesel-drinking engine ever to emerge from the BMW stable but that's still quite a title to have and it means that the 740d luxury saloon has plenty to live up to.
Modern diesel technology means that the best oil-burning engines are now more than capable of powering top end luxury cars in an appropriately serene and imperious manner. Some of BMW's rivals have developed eight and even ten or twelve cylinder engines to perform the role but six has been deemed sufficient in Munich and on driving the marque's 3.0-litre straight six diesel models, it's hard to disagree. The 740d utilises yet another development of this basic 3.0-litre engine but there isn't too much that's basic about it with BMW taking the opportunity to showcase what it understands to be the state of the large diesel engine art.
The 7 Series is a big chunk of automotive real estate at five metres long and very nearly 2,000kg. When you see one, the thought could easily creep into your mind that six-cylinders might be a couple shy of the optimum. Especially if the car is to provide the surging performance and effortless high speed cruising that should be the goal of every top line luxury car. Fear not. In the 740d, BMW has developed the twin-turbocharged version of its 3.0-litre diesel, as found in barnstorming models like the 335d and the 535d, to produce 306bhp and a king-sized 600Nm of torque from 1,500rpm.
"BMW's 740d is a car that will get the absolute maximum from its comparatively modest capacity"
Twin turbocharging is a great solution for diesel engines, many of which have been known to suffer from lag in their power delivery particularly at low revs. The BMW system combats this with a small turbo which gets going quickly, giving almost instant boost at low engine speeds and a large turbo that takes longer to get into its stride but gives the big kick that's required from medium revs to the red line. The 740d's engine can accelerate the car from standstill to 60mph in 6.3 seconds and bump up against BMW's 155mph speed limiter where conditions allow.
There's nothing particularly ground breaking about the way the 7 Series looks. The exterior lines are clearly derived from the previous generation car with elements carried over from BMW's other current products. The kidney grille is more upright and pronounced shoulder lines run the length of the car, ultimately forming the raised centre section on the bonnet. Inside, there's more of the same with design features that BMW owners will be more than familiar with. Where the 7 Series really moves the game on is in terms of its technology with all kinds of innovations being made available to customers with the money to afford them.
Amongst the highlights is night vision system that can detect and warn the driver if a pedestrian moves into the path of the vehicle. There's also a front side view camera system that activates cameras on the nose of the car to give the driver a better view at blind junctions. The Lane Departure Warning system monitors road markings and tells the driver if they wander out of their lane while the Speed Limit Warning System can actually read road signs and warn the driver if they exceed the speed limit.
Anyone concerned about parking and manoeuvring the 7 Series in tight situations will be interested in the Integral Active Steering system that allows the rear wheels to steer by as much as 3 degrees. This has a big effect on the car's turning circle and significantly enhances manoeuvrability at low speeds while also improving the driving dynamics when the pace picks up.
When specifying your 740d, it's the age-old BMW trim level choice of SE or M-Sport. The M-Sport package is an interesting inclusion on a luxury car like the 7-Series but remember that BMW places lots of emphasis on the way its cars drive, even in a sector where many owners will pay someone else to do the hard work while they recline in the back and operate a copy of the Financial Times. The M Sport package includes 19" alloy wheels, a body styling kit and a number of M Sport accessories in the cabin including a very fetching sports steering wheel and anthracite headlining. The firmer suspension settings that accompany M Sport models further down the range aren't included to preserve the luxurious ride of the 7.
BMW's Dynamic Stability Control + system comes as standard on all 7 Series models. Bundled up in this package are innovations such as Hill-Start Assist, Brake drying and pretensioning, Soft-stop and Brake Fade Compensation which are all designed to enhance safety and maximise the smoothness which the 7 Series goes about its business. The Dynamic Traction Control can be activated by the driver to allow greater wheel slippage for sporty driving or to enhance performance on snow and ice.
BMW's commitment to six-cylinder diesel engines in its luxury saloon might leave it vulnerable to being overpowered by larger-engined rivals but it gets its own back on economy. For comparison purposes, Audi's 4.2-litre V8 TDI diesel engine has 330bhp and 650Nm but its combined economy is some 10mpg worse than the 41mpg achieved by the 740d. Indeed, this higher powered twin-turbo version of BMW's 3.0-litre diesel is only around 1mpg less efficient than the 730d which has 245bhp and a single turbo. Emissions of 181g/km are a further advantage, particularly for business customers wary of their tax liability.
It's not merely the engine that makes the 740d's class-leading efficiency possible. BMW's EfficientDynamics technology has set the standard in a market where every mainstream manufacturer is taking steps to maximise economy and lower emissions. The 7 Series benefits from the full EfficientDynamics package with key body panels fabricated from aluminium to save weight and Brake Energy Regeneration using energy that would have been lost under braking or on the overrun to recharge the car's battery.
Some luxury saloon buyers might feel slightly inadequate with a mere six cylinders under their bonnet but BMW's 740d is a car that will get the absolute maximum from its comparatively modest capacity. The latest iteration of BMW's outstanding 3.0-litre straight-six diesel engine uses twin turbocharging to achieve its 306bhp but it's the fuel economy that will really give it an edge amongst the market's big hitting luxury diesels.
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|BMW 7 Series 740d M Sport 4dr Auto diesel saloon|
|Price £57,631||Save £12,949|
|BMW 7 Series ActiveHybrid 7 SE 4dr Auto saloon|
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|BMW 7 Series 730d BluePerformance SE 4dr Auto diesel saloon|
|Price £52,886||Save £6,224|
|BMW 7 Series 730d M Sport 4dr Auto diesel saloon|
|Price £52,250||Save £11,140|
|BMW 7 Series 750Li SE 4dr Auto saloon|
|Price £66,459||Save £7,881|
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|For 7 SERIES 740d|
|OVERALL||7.9 OUT OF 10|
|Space / Versatility||8|
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