Diesel enhances X5 performance

MERRICKVILLE, Ont. – It was a frigid -17C - the perfect weather in which to put BMW’s new diesel-powered X5 sport utility to the test.

Once, not so long ago, such cold would have resulted in “the Rudolf Diesel memorial minute” – the time needed for the electric glow plugs to warm the engine enough for combustion to take place. (Remember, a diesel has no spark plugs; combustion is purely a result of fuel and air igniting under high compression.)

But even on this chilly Ottawa Valley morning, the 3.0-litre diesel powering the 2009 X5 roared instantly to life. Well, perhaps “roared” is the wrong word. These modern oil-burners are so quiet that no diesel clatter is evident in the cabin, either at start-up or under heavy loads, and it’s barely audible to those standing outside, within a few feet of the hood.

They’re also incredibly fuel efficient and clean burning. In fact, the 3.0-litre is so efficient, even at idle, it needs an electrically-powered ceramic boost heater to keep the cabin toasty warm.

Also found in the 2009 335d sedan, the 265-hp, 3.0-litre straight six is the first of BMW’s advanced diesels with BluePerformance (named for the blue of a pollution-free sky) to be made available in Canada. This inline six powers a wide range of European models and has been named International Engine of the Year several times.

It’s not only efficient, thanks to the precise fuel management of its third-generation common rail direct-injection, but clean burning and in full compliance with emissions standards in Canada and all 50 U.S. states.

Like other BluePerformance diesels, this one utilizes an oxidation catalyst placed close to the engine, a particulate filter housed in the same unit and an SCR catalyst with urea injection. This combination effectively reduces nitrogen oxides (NOx) through a chemical reaction in the exhaust system that’s initiated by injecting a small amount of urea called AdBlue. BMW says the ammonia generated in this process converts the NOx in the exhaust gas into environmentally friendly nitrogen and water vapour.

AdBlue is non-toxic and non-flammable and anyone can refill the easily accessible tank – you don’t have to take the vehicle back to the dealership. Because the technology has been used on large trucks for some time, AdBlue is readily available at truck stops. The system holds 23 litres, which should last the whole oil change cycle of 20,000-24,000 km.

Tom Baloga, VP of engineering for BMW North America, says the new engine offers “four-cylinder fuel economy with V12 torque.”

And since the gas-powered X5 burns premium unleaded, the per-litre price gap isn’t as great as it would be between the diesel and a vehicle that uses regular 87-octane gasoline.

BMW anticipates that the X5 xDrive35d will offer improved fuel economy of 26.7% city and 19% highway over the gasoline-powered X5 3.0si.

As for performance, the xDrive35d is a full second quicker from 0-100 km/h than the 3.0si, with a time of 7.2 seconds.

Baloga says the incredible torque of the diesel – 425 lb.-ft. at 1,750 rpm – works really well in the X5 because many owners will want one for its towing capacity of 6,500 lbs. Because of all that torque, the six-speed automatic normally mated with V8 engines is used with this engine.

The xDrive35d also has both high and low pressure exhaust recirculation to reduce NOx emissions when towing.

At 89.3 hp per litre of displacement, it’s the highest output of any production diesel sold in North America.

Resale values are expected to be high because of the longevity of the diesel engine.