First drive: BMW's fluid off-roader

IT'S BEEN a long time coming, but BMW Australia has finally joined the growing band of manufacturers to offer turbo-diesel power.

In fact, the spinning propeller brand's first ever diesel model sold Down Under, the X5 3.0d off-roader, could be the start of a revolution in turbo-diesel motivation for BMW passenger vehicles in the land of the V8.

BMW makes no bones about the fact X5 3.0d - first deliveries of which begin in April - represents an exercise in establishing turbo-diesel technology as part of the BMW range.

While next year's 3 Series-based X3 off-roader, the X5's little brother, is also eventually likely to comprise a turbo-diesel model, BMW plans to offer similar versions of future sedans - including the mainstream 3, 5 and 7 Series model lines - that centre around the success of oil-burning X5 and X3 models.

So expect BMW to put plenty of resources into pushing the turbo-diesel wheelbarrow from about now.

Of course, BMW is hardly a diesel power pioneer locally, especially when it comes to the off-roader world. All-terrain wagons like Toyota's LandCruiser, Nissan's Patrol and the Holden Jackaroo have offered diesel power for many years.

The Land Rover Discovery/Defender has led the European charge, joined in early 2000 by Mercedes-Benz's popular ML270 and Audi's successful Allroad Tdi.

Mitsubishi has vastly uprated its diesel presence with its excellent Pajero DiD, while Jeep's Cherokee and Grand Cherokee are the latest off-roaders to offer the sparkplug-less engine.

Then there are diesel-powered passenger cars like the Benz E-class, Peugeot 406 and Citroen C5 that have long attracted a strong following, and even brands as diverse as Volvo and Holden have openly stated their desire to offer diesel power.

The introduction here of the fourth BMW X5 model (joining X5 3.0i, X5 4.4i and the X5 4.6is range-topper) was delayed until the introduction of a new federal standard of diesel fuel quality, which came into effect on January 1 this year.

BMW says the changes, which reduce the sulphur content of Australian diesel fuel from around 1700 parts per million to just 550ppm, bring our fuel within the technical tolerances of the X5 3.0d's Euro III-compliant engine.

Despite this, the same engine has been offered in the Range Rover SE and HSE since its launch in August 2002.

Either way, what BMW describes as "the world's most advanced diesel-engined Sports Activity Vehicle" is here, and the X5 3.0d makes a compelling statement in terms of driveability and economy, especially when compared to the previous entry level X5, the 3.0i six-cylinder petrol.

On sale Down Under at an introductory price of $78,000 for the five-speed manual and $80,000 for the five-speed auto (each undercutting the X5 3.0i by $2700), the X5 3.0d carries an identical standard equipment list to the 3.0-litre petrol X5.

This includes traction and stability control, no fewer than 10 airbags, ABS, Hill Descent Control, DataDot security, 17-inch alloys, roof rails, front foglights, remote central locking, "Dakota" leather upholstery, multi-function steering wheel, in-dash CD audio and luggage net.

Almost identical to X5 3.0i, X5 3.0d differs only in its use of a diesel (but still straight six) engine, different (but still 17-inch) alloy wheels and concealed exhaust outlets. Options prices are also as per X5 3.0i.

So X5 3.0d makes a persuasive argument on a price versus specification basis, but the story gets even better when it comes to mechanicals.

Featuring a slightly smaller displacement (2.926 litres) than the petrol six-cylinder engine with over-square (88 x 84mm) bore dimensions, 18:1 compression and four valves per cylinder, the common-rail turbo-diesel engine produces 135kW at 4000rpm and a big 390Nm of torque at 2000rpm.

While the 3.0i produces more power at more revs (170kW at 5900rpm), the diesel blows it away for torque, with the petrol engine delivering only 300Nm at a much higher 3500rpm. Despite the extra torque, the taller-geared X5 3.0d returns impressive fuel consumption figures.

In manual guise, the 3.0d achieves 9.3 litres per 100km (versus 13.9 for the 3.0i) in the city and 6.4L/100km (versus 8.9 for the 3.0i) on the highway. Overall, by BMW's own figures, the 3.0d (8.0L/100km) uses 3.6 litres less fuel for every 100km than the 3.0i (11.6).

A 190km/h top speed falls short of the 3.0i's 202km/h flat-strap figure, as does 0-100km/h acceleration, which at 10.5 seconds in manual form is exactly two seconds slower than the 3.0i. The gap falls to less than a second in BMW's claimed 80-120km/h test, which the 3.0d completes in 8.5 seconds to the 3.0i's 7.6.

In a nutshell, for $2700 less than the X5 3.0i, buyers of the X5 3.0d get the same equipment level, the same 25,000km service intervals, "similar" servicing costs, better driveability and a massive 1100km range from the same 93-litre fuel tank.

While these days there is no significant cost saving on the fuel itself, the Federal Chamber of Automotive Industries is lobbying for greater price parity between petrol and diesel. And major petroleum distributors have undertaken to improve diesel fuel's other main negative, bowser cleanliness.

BMW has sold 4500 X5s since going on sale here in November 2000 and again expects to sell between 1700 and 2000 examples this year because it is limited in supplies form the Spartanburg factory in the US. Between 200 and 300 of these are expected to be diesels.

PRICING:
X5 3.0d manual $78,200
X5 3.0d auto $80,800
X5 3.0i manual $80,900
X5 3.0i auto $83,500
X5 4.4i auto $109,500
X5 4.6is $152,300

DRIVE IMPRESSIONS:

WHEN a company like BMW makes the step to offer diesel power for the first time in Australia, you gets the sense it's time to pay attention.

Unlike in some European nations where up to 65 per cent of passenger vehicles are diesel-powered, diesel motivation has never transcended the utilitarian transport or off-roader market in Australia.

Which is a shame, because oil-burning technology - particularly the type that's accompanied by a turbocharger - has reached a level of convenience, refinement and efficiency that would make even the most die-hard petrol engine lover stand up and take notice.

Take the X5 3.0d. Gone is the need to wait for a glow plug indicator in the dashboard to turn green before starting. Gone is the clattery, coffee-grinder style of engine note and, thanks to vacuum-operated hydraulic engine mounts, gone too is the pronounced engine vibration normally associated with diesel power.

There is a degree of black smoke emitted from the concealed tailpipes (along with subtle front quarter badging and different wheels, it's the only giveaway this is not a X5 3.0i) upon start-up when cold, but this quickly reduces once warm and from within the X5's well isolated cabin there's little to remind the driver of what lurks beneath the bonnet.

Until you squeeze the accelerator pedal, that is. With no less than 390Nm of torque at just 2000rpm - almost 25 per cent more than the six-cylinder petrol X5 3.0i, produced 1500rpm further down the rev range - the X5 3.0d comes with some significant performance credentials.

The simple fact is that with a similar kerb weight, the diesel X5 produces more torque at fewer revs, making it easier for the 3.0d driver to make use of its greater reserves of grunt. Now, thanks to shorter gearing, a much higher redline and (as a result of this) more peak power, the 3.0i remains quicker from a standing start to 100km/h.

But, BMW's own figures show, the gap is narrowed to an almost insignificant figure in the 80-120km/h acceleration (read: real-world) test. And the X5 4.4 V8 isn't as far ahead of either six-cylinder model as you might think. Thank gadgetry like variable turbine geometry and much higher fuel injection pressure and volume control for the un-diesel-like performance.

The over-riding feeling behind the wheel of the 3.0d is one of superb driveability and midrange urge. Sure, a degree of lag does accompany sudden throttle inputs, and best results are achieved by short-shifting before the impressive wall of torque drops off around 4000rpm.

But a chance to back-to-back the 3.0d with the 3.0i revealed that, at least in the driving situations we encountered during the launch, the diesel vehicle is more responsive, more tractable and more satisfying.

In a significant move, BMW held most of the 200km X5 3.0d launch over unsealed roads. There were regular dirt roads, of course, but in an effort to prove X5's off-road ability, linking them were a number of reasonably testing logging tracks and fire trails through state forests - some of which necessitated the use of the X5's excellent Hill Descent Control, others comprising fairly nasty log and rock crossings.

While the route was nothing the likes of a Toyota Rav4, for example, couldn't handle, car-based "soft-roaders" would certainly have been out of their depth and it was with impressive ease that the X5 handled everything dished out to it.

Ground clearance, while relatively healthy, was its most limiting factor, with underbody protection and even traction from the tarmac-biased tyres on the loose but dry surfaces both proving their value. Of course, this is no Range Rover, but what X5 loses off-road, it tends to compensate for on the blacktop.

On the short but winding bitumen stretch back into town, the diesel wagon proved once again the X5's considerable road-going prowess. Of course, the 3.0d offers the same level of grip, relative lack of bodyroll and the powertrain's refreshing 62 per cent rear torque bias as the 3.0i, making it a tenacious road performer in the right hands.

The 3.0d, however, adds ever-willing turbo-diesel performance to the tried and proven X5 equation, including brilliant five-speed Steptronic auto, which brings a level of driveability not found in the similarly priced petrol X5.

Throw in far superior fuel economy and the X5 3.0d makes a convincing, if at least more logical argument indeed.

Now, if only Aussie buyers had the choice of 3, 5 or 7 Series sedans with the same great diesel engine, as BMW buyers do in Europe...