At the 2007 Detroit Auto Show, BMW was prominently displaying their diesel engine technology, particularly the latest 3.0L twin turbocharged in-line six cylinder. At the time, BMW spokesman Daniel Kammerer told us that BMW would be introducing that diesel engine to the U.S. market later in 2008. BMW still hasn't said which vehicles would get the diesel although it's expected that that the first installations will be in the X5 SUV and 5 series sedans and possibly the new X6 crossover.
Here at the AutoblogGreen Garage we just couldn't wait another whole year to try out a diesel BMW and when we found out that Bosch had one the pestering began. As a supplier of diesel engine fuel and emission control systems, Bosch has a vested interest in the success of diesel engines. To that end, they have brought over a fleet of European diesel vehicles, many of which are expected to be on sale in the US over the next couple of years. Earlier this year we sampled the Chrysler 300 and Smart ForTwo diesels. The Chrysler in particular was very impressive, but this BMW was in a whole different class. Find out how the BMW 535d fared in the ABG Garage after the jump.
BMW briefly sold one of their early diesels in the U.S. market in the form of the 524td in 1985-86. That same 2.4L six cylinder turbo-diesel was even offered as an option in the Lincoln Continental of the same period. Like most diesels of that time it wasn't particularly powerful but it was smoky and noisy to compensate. With the passage of two decades, things have changed pretty dramatically. More than half the cars BMW sells in Europe today are powered by a variety of four-, six- and eight-cylinder diesel engines. For our test Bosch turned over a 2007 BMW 535d SE for a week's worth of driving.
The current generation E60 5-series has been with us since 2004 and the styling went a long way toward redeeming Chris Bangle. It didn't have any of the awkwardness of the earlier 7-series or the excessive surface development of the Z4. The muscular proportions look particularly handsome in the dark Monaco Blue of the test car. Starting at the front bumper the bodywork surrounding the twin kidney grille sweeps back to the A-pillars with a pronounced chamfer preventing it from looking too bulbous. On either side of the grille the headlamp clusters sweep back into the front fenders blending into a character line that runs the length of the body.
On both sides of the grille and in the rear bumper are proximity sensors for the parking assist system. During low speed maneuvering such as in a parking lot, the screen in the dash displays a plan view of the car showing any objects close to either end of the car. Sitting at a stop sign or traffic light a pedestrian walking in front of the car will set off an alarm if the system is turned on. Below the front bumper is a radar sensor for the adaptive cruise control system. This monitors the distance to the car ahead when the cruise control is engaged. If the car slows down, or someone pulls into the gap, the BMW automatically applies the brakes to maintain a pre-set distance. It then holds the lower speed until traffic ahead speeds up or you pull out to pass.
That same display in the center of the dash also an integral part of BMW's I-Drive system. As new cars kept adding more features and functionality over the last decade, buttons were needed to control it all. In response BMW created a large control knob on the center console that acts as a combination mouse, joystick and all-purpose knob. When it debuted on the current generation 7-series, it was roundly panned as being far more complicated than even having a mass of buttons. More recently, other companies such as Honda and Audi have utilized similar controllers on a variety of models. Having recently tried both the Acura RL and Honda Accord, I can say that the control knob idea can actually be made to work very nicely. It's not the hardware that's wrong in I-Drive. It's BMW's software interface that's absolutely horrendous. They need to completely trash the I-Drive software and contract someone that knows a thing or two about human-machine interface design to create a new GUI.
Thankfully, as bad as the I-Drive software interface is, the rest of the 5-series interior is mostly wonderful. Given the performance capabilities of this car, the front seats are a godsend. If you can't find a comfortable and supportive setup in these seats it's probably because your spine has been tragically contorted by some crippling malady. It might take you a couple of minutes to go through all the adjustments, but it will be worth it. The thigh support is longitudinally adjustable helping to avoid my most common seat complaint, that of too short bottom cushions. The lumbar support is adjustable for both size and vertical position. The lateral supports are adjustable for width to keep you in position during hard cornering. Even the shoulder support is adjustable.
The 535d arrived just as Michigan was getting it's first snow of the season. Thankfully there was some relief from the cold in the form of heated seats both front and rear. Changing direction was facilitated by a wonderfully thick rimmed steering wheel which framed clear legible gauges. The 5-series features dual zone automatic climate control so that each passenger can select their own comfort level. Fortunately, Bosch swapped the high-performance summer tires for a set of Continental ContiWinterContact tires in a 245/35R19 size. If you've ever driven in winter conditions with proper snow tires, you'll never want to go back to all-season tires. Real winter tires can provide immense grip even when putting down the torque of a monster diesel like the one in this BMW.
While the diesel engines of twenty years ago were thrifty with fuel, they did earn the reputation which diesels hold among American consumers to this day: slow, noisy and smoky. While that reputation may have been deserved then, nothing could be further from the truth today. The engine in the 535d is a 3.0L in-line six cylinder in the classic BMW configuration. Fuel is delivered directly to the combustion chambers via a Bosch Piezo Common Rail injection system and air is pumped in by a pair of turbochargers. The result of all this high-pressure action is 286 hp and, more importantly, 428 lb-ft of torque at only 1750 rpm. As with all diesels this is not a high revving screamer with the red-line at a relatively modest 5,000 rpm. However the almost flat torque curve combines with a 6 speed automatic transmission to provide fabulous acceleration that never seems to let up. If feels more like an electric motor if you ignore the pleasant exhaust growl. BMW rates the acceleration from 0-62 mph at 6.4 seconds and that was backed up by my informal observations, even on less than dry pavement.
Judging from the previous paragraph you might think this review belongs on Autoblog rather than ABG. While it would certainly be well placed there, this sport sedan is here to demonstrate that the refinement of modern diesel engines hasn't sacrificed the fuel thriftiness that old Rudolf's engines are known for. This 3825 lb luxury sport sedan achieved this performance while still going 27 miles on each U.S.-sized gallon of ultra-low-sulfur diesel during it's time on our garage. That's comparable to the much smaller Nissan Versa I drove several months ago and significantly better than the 2008 Scion xB that only managed 23.4 mpg. In fact the only vehicles I've tested this year that did better were the Nissan Altima and Ford Escape hybrids which got 32 and 30 mpg respectively. A significant portion of the driving in the BMW was in the city as well which makes it even more impressive. On the EU highway cycle, the 535d is rated at 43.5 mpg (U.S.).
The engine in this particular car was compliant with current Euro IV standards, meaning it's not fifty-state legal in the U.S. It is equipped with a particulate filter and never emitted any visible smoke or odors. Operation was smooth and quiet enough not to offend anyone. However this Euro-spec car emits too many nitrogen oxides to pass Tier 2 Bin 5 requirements. When BMW does introduce diesel engines to the U.S. they will be equipped with a urea injection system like the one already used by Mercedes-Benz on the E320 BlueTec. BMW hasn't officially announced which vehicles will get diesels other than saying they would come some time in 2008. Expectations are that the 5-series and the X5 will be the first US market BMW diesels since the 524td. So far, BMW has said the new 1-series will only have six cylinder gas engines in the US market. After thoroughly enjoying a week with this 535d, hopefully the new fuel economy regulations will prompt BMW to change their mind and bring the 123d to the U.S. A 123d running on B100 would be some serious green driving fun.