Last Wednesday, BMW accepted two Ward's Automotive Group awards for its engines: both are twin-turbo inline sixes, one powered by gasoline and the other by ultra-low sulfur diesel. Direct injection, low-mass twin turbochargers, and high-strength aluminum construction enable both powerplants to offer unparalleled levels of power, efficiency, and refinement.
The twin-turbo gasoline unit finds its way into eleven BMW models for the 2009 U.S. market including the 135i, 335 sedan and coupe models, the 535i sedan, and the X6 xDrive 35i SAV. The twin sequential turbocharged 3.0-liter diesel six is new to the U.S. for 2009, and will be featured in the 335d sedan and the somewhat awkwardly-named X5 Xdrive35d. Performance figures for these diesels are far from pokey, thrusting the 3-series sedan from rest to 60 mph in 6.0 seconds flat, the X5 in 6.9. And even with 425 lb-ft on tap, the 335d manages 36 mpg and the X5 Xdrive35d 26 mpg, both highway figures.
In a world where packaging efficiency has led most automakers, even Mercedes, to abandon the lengthy inline-six in favor of a more compact V-6 layout, BMW has stuck resolutely to its legendary inline six. One of the smoothest engine configurations possible due to evenly-spaced power pulses at the crankshaft, BMW inline sixes love to rev and do not require counter-rotating balance shafts for silky smooth operation.
2009 BMW 335dEnlarge Photo