Introduction
BMW introduced its first diesel engine vehicle in 1983. Mounted under the hood of a
5 Series sedan, the 2.4-liter, turbocharged diesel engine in the 524td
would accelerate the vehicle to 60 mph in about 14 seconds. BMW touted it as the fastest diesel in the world, with a top speed of 112 mph. It was sold for a short time in the United States before it was pulled from the domestic marketplace.
BMW engineers continuously developed diesel technology over the next 25 years, and demand for BMW diesel engines has grown worldwide. According to the manufacturer, 67 percent of all new BMWs delivered to customers in Europe are powered by diesel engines. Much more sophisticated and refined than their predecessors from two decades earlier, and no longer carrying a negative reputation, diesel powerplants have won praise for their efficiency. On average they consumer 25-percent less fuel than an equally powerful gasoline engine, with higher torque and longevity, BMW says.
The Powerplant
BMW is once again introducing a diesel powerplant to the U.S. market later this year: a 3.0-liter, inline 6-cylinder model featuring BMW's Variable Twin Turbo Technology. BMW states this engine is widely acknowledged as the unchallenged benchmark for sporting performance, motoring refinement, and superior efficiency in other markets around the world. With exceptional power, torque and low emissions, it is particularly well-suited for BMW's premium vehicles, BMW notes, adding that this new engine generates ony one percent of the particulate emissions originally contained in the exhaust gas of the 524td in 1983.
All aluminum in construction, the engine features third-generation common-rail direct fuel injection. This fuel delivery system employs precision-quality piezo-injectors to deliver precise amounts of fuel directly into the combustion chambers. The result is combustion optimized for emissions, fuel economy and running smoothness, BMW says.
Two turbochargers are used to boost engine power. A smaller turbocharger, with low inertia, is activated at lower speeds. This first turbo is designed to respond to the smallest movement of the gas pedal and increase engine power without the slightest delay. As engine speed increases, a larger second turbocharger cuts in to help develop maximum horsepower and torque. The resulting powerplant is one of the most economical and fuel-efficient engines in its class, BMW claims. It's rated at 265 hp, producing 425 lb.-ft. of torque at 1750 rpm.
Innovative Emission Reductions
To ensure compliance with the demanding emission standards in California and the other States, the engine is 50-state BIN5 compliant-exhaust gasses are scrubbed before they leave the tailpipe. Exiting the combustion chamber, harmful exhaust emissions are cleaned and reduced by incorporating an oxidation catalyst downstream of the exhaust manifold.
A diesel particulate filter is also placed downstream along with an SCR catalyst with urea injection: a small dose of urea called "AdBlue" placed into the exhaust stream, which causes a chemical reaction that converts nitric oxides (NO and, respectively, NO2) into environmentally compatible nitrogen (N2) and water vapor (H2O). These measures ensure even the smallest particles are filtered from the flow of exhaust gasses, and nitric oxides (NOX) are effectively reduced, BMW explains.
The AdBlue urea additive is stored in two different heated tanks within the vehicle. (The heaters prevent the chemical from freezing at low temperatures.) The chemical itself is clear, non-toxic and safe to handle. With a very low consumption rate, it ordinarily needs to be replenished only when the oil needs changing. BMW states the refilling of the AdBlue tanks will be a no-charge service for the first 4 years or 50,000 miles under BMW's Maintenance Program.
Two New Models
BMW Advanced Diesel technology is being introduced into the U.S. market under the hood of the
X5 and
3 Series. In the X5, the new diesel engine will power the X5 xDrive35d. In the 3 Series, the new model will be designated the 335d.
The BMW 335d with the Advanced Diesel offers performance that exceeds that of the 328i, its gasoline-powered sibling. With the powerful, 3.0-liter twin-turbo diesel driving the rear wheels, the 335d will accelerate to 62 mph in just 6.2 seconds, BMW claims. Average fuel economy will be 23 mpg city/33 mpg highway (preliminary BMW estimates). Like the 3 Series sedan, the X5 is transformed by the powerful diesel. The all-wheel-drive X5 xDrive35d will accelerate to 62 mph in just 7.2 seconds, BMW says, topping the performance of the gasoline-powered X5 3.0si by more than half a second. Fuel economy estimates on the X5 are 19 mpg city/25 mpg highway. Both models will appear in BMW showrooms in late 2008.
