In 2012 at the Geneva Motor Show, BMW introduced their BMW M Performance Automobiles line which includes the BMW M550d xDrive (sedan and touring), BMW X5 M50d and X6 M50d. These high performance diesels are powered by an all-new tri-turbo engine, the very same engine that was used later in the year in a high-end 7 Series model. The BMW 750d xDrive launched later in 2012 and was made available in Germany with the short and long wheelbase.
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By fitting an engine that could have powered an “M5 diesel” model, the Bavarians are giving their high-paying customers access to a luxury sedan paired with an all-wheel drive system that offers the driving safety much needed on the snowy German roads in the somewhat long winters.
BMWBLOG traveled to Munich earlier this year to test drive yet another BMW that we won’t see on this side of the pond. Just as the airplane touched the ground, Munich was starting to be hit with one of the biggest and longest snowstorm of this German winter, an ideal situation to find out how the large sedan handles itself.
What matters the most in this 7 Series – The Tri-Turbo Diesel Engine
We first experienced the 3.0 liter tri-turbo unit in the M550d Touring xDrive model and the innovative engine packaged with the sporty and fairly compact touring surpassed our expectations. “In just a few days and over a few hundred miles, the M550d Touring has won my heart, not only with its power, but also with its elegant and aggressive design, and versatility,” we reported at the time. The N57S 3.0 liter straight-six tri-turbo units develops 381 horsepower at 4,4000 rpm and 740 Nm (546 lb-ft) of torque served up between 2,000 and 3,000 rpm.
With 93.6 kW/127.3 hp per liter of displacement, the N57 sets a new benchmark standard for diesel engines. To achieve this goal, BMW has not only added a third turbocharger, but also engineered a new aluminum crankcase, common-rail direct injection with piezo injectors and high-pressure turbocharges with variable turbine geometry. The maximum injection pressure is 2,200 bar. The system comprises two relatively small turbochargers and one large turbo, which join forces precisely to deliver the amount of power required.
To handle the monster torque BMW paired the powerful diesel with the eight-speed automatic transmission known from other models. 0 to 100 km/h (62 mph) is achieved in 4.9 seconds, just a tenth of a second slower than the more 750i with its V8 and 406 horsepower. BluePerformance emission control option is included with 750d xDrive and 750 Ld xDrive therefore the CO2 levels are fairly low at 169g/km.
Dressed up as a “regular” 7 Series model
Visually the BMW 750d xDrive looks just like the other models in the lineup. The facelift introduced in 2013 brought some small but interesting visual changes. The 7 Series LCI gets new “squarish” LED corona lights with an LED turn signal indicator placed in the headlight. While the previous model featured a kidney grille with 9 and 12 slats, based on the Night Vision Camera option, the facelifted 7 comes now with a single configuration of 9 slats. The fascia also gets more chrome than before, starting with the area surrounding the grille. Two chrome bars are now part of the front apron which also sports larger air intakes that give the car a sportier look.
Inside, the biggest change we noticed was the new 3D MMI system that brings out a refreshed design with a new CPU that renders the information faster than before. The map feature now displays 3D city models for selected cities; Munich was on that list. High quality leather, wood and materials are exactly what you would expect from a 100,000 Euros limousine, and we have not been disappointed.
According to the driving situation, the low moment of inertia of the small turbochargers is exploited to the full to deliver razor-sharp responses, while the link-up with the large turbo is maximized to generate as much charge pressure as possible.
Not only fast, but also very efficient
One would be inclined to think that 740Nm of torque paired to 12″-15″ of snow is simply a bad idea, but the flagship diesel 750d and its xDrive system surprised us. In a pleasant way. Thanks to the winter tires and the 40:60 rear-biased xDrive, the high-end 7er diesel had no problem gaining traction on snowy roads and despite pushing the car hard through some sharp corners, stability was not a concern while understeering was expected. The xDrive and its variable torque split has the ability to transfer up to 100 percent of the available power to either axle should slippage occur, so it maximizes traction at the cost of some understeer.
Just like the other 7 Series models, the Driving Experience Control is standard giving us the option to choose between the SPORT, SPORT+ or COMFORT+ driving modes. While most of our test drives are done in the Sport modes, the heavy snow and somewhat difficult road conditions made us choose the smoothness of the COMFORT+ driving mode, an excellent choice for the Autobahn during long rides. After a few days and some inches of snow melting, we took the 750d xDrive through some back roads to test its sporty abilities. Limited by the winter tires specifications, we stayed below 200 km/h but fast enough to give us a feel of how the heavy limousine handles itself when pushed through some corners. This is where the extra traction, when compared to the rear-wheel drive variant, came in handy.
The 381 horsepower are more than enough for this type of car, especially when coupled with the massive torque that throws you back in the chair while quickly, yet smoothly, shifting through all the gears. The centerpiece of this story is without a doubt the impressive torque levels achieved by this innovative engine that we only hope we would see in future products, maybe with an even higher output.
Our test drive model returned a fuel consumption of 36 MPG combined.
Should I buy one?
If you enjoy diesels, have enough money and appreciate the latest and best German engineering, then the 750d xDrive is for you. Despite its base price tag (88,500 Euros) and an endless list of expensive options, the high-end diesel limousine offers a lot for the money, and can be considered one of the most versatile models in the 7 Series family. It is fast, it is fun, looks and feels premium, and can be driven all year-round, from your cabin in the mountains to the high-speed Autobahn.
But for now, only the Germans get to enjoy this fine piece of sublime engineering.
Here is a video from FloWeGoPro that shows the acceleration of the 750d xDrive: