Four-Turbo Diesel Next Up for BMW?

BMW AG is working on a new diesel boosting system that would integrate four turbochargers, according to a report in Bimmer Today. The online enthusiast site says the system, described as the first-ever quad-turbo design, would replace the triple-turbocharged 3.0-liter straight-six engine BMW launched in 2012.

Codenamed B57 TOP, the quad-turbo diesel is expected to generate 408 hp and 590 lb-ft. of torque, according to the report. BMW says the latter statistic is a record for 3.0-liter diesels. The engine would be paired with an 8-speed automatic transmission and send power to all four wheels.

BT says the design could team a pair of small turbos with two larger ones, or all four could be different sizes. Another option: adding an electric turbocharger to the current all-mechanical tri-turbo system.

In addition to increased output and a broader power band, the quad-turbo design could virtually eliminate turbo lag and improve fuel efficiency, BT speculates.

The new engine could bow as early as next March at the Geneva auto show. As with the triple turbocharger, the quad unit likely would be limited to BMW's high-performance M lineup.