Bad news for diesel fans: according to BMW Blog, BMW is planning to discontinue its ludicrous 400-horsepower quad-turbo diesel engine next year, leaving its top-performing diesel passenger vehicles with a weaker twin-turbocharged diesel mill. The engine pumps out a dramatic 560 lb-ft of torque from just 2,000 rpm, propelling the BMW M550d xDrive sedan from 0 to 100 kph (62 mph) in just 4.4 seconds.

BMW's high-performance quad-turbo diesel engine is also available in the M550d Touring, the 750d and 750Ld sedans, and the BMW X5, X6, and X7 M50d models, where it delivers similarly remarkable performance.

Alas, the world is less hospitable to diesels in the wake of companies like Volkswagen being discovered installing "cheat devices" to circumvent strict nitrous-oxide emissions regulations, and BMW Blog also cites rising CO2 emissions restrictions as an impetus for the BMW quad-turbo engine's impending demise. Despite its potency, though, the six-cylinder quad-turbocharged engine achieved a fuel economy rating of around 38 miles per gallon in the M550d.

The new diesel-burning top dog in BMW's lineup will be the twin-turbocharged engine found in the automaker's 40d models, which has been tuned to produce as much as 330+ horsepower.

Of course, BMW put an end to all diesel engine sales in the US market after the 2018 model year, meaning there's some question as to how much we should care on this side of the pond. Instead of the M550d, this market gets only the excellent, petrol-fueled BMW M550i xDrive, which rockets to 60 mph in under 4 seconds, courtesy of a 4.4L gasoline V8 with 523 horsepower on tap.

Instead of relying on diesel power, BMW appears to be addressing concerns over fuel economy in the US market by expanding its selection of plug-in-hybrid powertrains, with models like the BMW 530e and 745e. Numerous additional BMW hybrid models are on the way.