1. The diesel X5 is rated at 18/26 mpg (city/highway) compared to 15/21 mpg and 14/19 mpg for the xDrive30i and xDrive48i respectively
2. BMW has engineered new technology into its diesel engines to ensure they operate smoothly and quietly. On such invention is offset piston wrist pins which stops that rattling sound when the pistons move against the combustion chamber walls.
3. The xDrive 35d has a towing capacity of 6,500 lbs – 500 lbs more than the I6 and V8 gasoline X5 models.
Knowing full well that introducing premium luxury vehicles with diesel engines to North America will be an uphill battle, BMW engineers have gone to great lengths to ensure that they will not only meet our expectations, but that they will exceed them. This has been an ambitious project from the get-go as transforming negative perceptions is never an easy task – especially when it comes to the discriminating tastes and expectations of premium automobile buyers. Goals for this project consisted of such things as reducing CO2 emissions and improving fuel economy, all the while preserving the driving enjoyment and performance for which BMWs are known. Like I said, no easy task.
In order to build a diesel SUV that didn’t drive or sound like a Mack truck, BMW employed a host of specific strategies to ensure the 35d version of its new X5 model would be attractive to North American consumers. For starters, the piston wrist pins have been offset in order to prevent pistons from rattling against the combustion chamber wall, thus reducing the ‘pinking’ sound commonly associated with diesels. Another addition is a cast reinforcement beneath the crankcase in order to add structural rigidity and prevent noise.
Along with a lengthy list of technological advancements, one of the most important was made to reduce emissions. BMW devised a system whereby diesel exhaust fluid (DEF) is sprayed into the exhaust just before the catalyst. This then creates a mixture that enters the catalyst where a chemical process changes harmful Nitrogen Oxide (NOx) into Nitrogen and water vapor. The result of these technological advancements is a significant reduction in greenhouse gases and a quieter, cleaner running automobile that can be sold in all 50 states.
The twin turbo setup for this particular motor is equally impressive. The system is comprised of a small, low inertia turbo, a larger turbo, a wastegate, and butterfly valves, which allow either the small, large or both turbos to operate simultaneously. Coordinated by a sophisticated ECU, power delivery is strong, linear and virtually free of turbo lag. This I felt immediately while driving the X5 xDrive35d. Stepping into the throttle provides a serious rush of acceleration at incredibly low rpm. Not only does the diesel inline-six engine create 265 hp at 4200 rpm, (the 3.0i makes 260 hp at 6600) but it boasts 425 ft-lbs of torque at 1750 rpm where the gasoline 3.0i powerplant makes just 225 at 2750 rpm.
Preliminary acceleration numbers demonstrate that the xDrive35d hits 60 mph a full second faster than the gasoline 3.0-liter six-cylinder version. Fuel economy is also impressive. The diesel X5 is rated at 18/26 mpg (city/highway) compared to 15/21 mpg and 14/19 mpg for the xDrive30i and xDrive48i respectively. BMW claims the added fuel economy will give the xDrive 35d a total range of 585 miles, as compared to 510 and 450 miles for the I6 and V8 gasoline versions.
Tom Bologa, the Vice-President of Engineering for BMW North America explains that “Providing a diesel engine in the X5 is appropriate because of the huge boost in fuel economy, but also due to the increase in torque for towing applications.” Thanks too all the low down torque the xDrive35d is rated for a towing capacity of 6,500-lbs – 500-lbs more than either the I6 or V8 gasoline engines. No need to hire out those boat-towing duties anymore as X5 owners can do it themselves.
Another hurdle that diesel technology faces is price. In addition to an increase in the initial cost of ownership, diesel fuel is also more expensive at the pumps, which scares off many potential buyers. According to Bologa, these numbers can be deceiving. “For both performance and emission purposes, we compare diesel to premium gasoline.” Higher octane premium gas is much closer in price to diesel than the lower octane gas that consumers are using as a reference point. This should be even more obvious for existing BMW owners who shouldn’t be choosing anything but premium at the pumps anyway.
In terms of initial expense the xDrive35d is priced at $51,200; more than the $47,500 inline-six model but still significantly less than the $56,200 asking price for the V8.
According to Bologa there are other factors that help to offset the initial cost over time. “The premium price of diesel vehicles and fuel are offset by improved fuel consumption and higher trade-in value.” Diesel engines typically experience increased longevity because they rev lower and diesel fuel is more of a lubricant than gas, so engines last longer by design.
To summarize, the X5 xDrive35d offers exceptional power and fewer emissions when compared to its gasoline counterpart – all in a clean and quiet diesel package. The most important aspect, however, might be that the typical spirited driving dynamics for which BMWs are known have not been compromised.
We may question their choice in music and beach attire, but these Europeans sure do know a thing or two about their automobiles.
Whisper quiet diesel engine
Initial purchase premium