*European Model Shown.

The first unofficial photos have surfaced online of the twin-turbocharged 4.4-liter V8 that will power the next-generation BMW M5. The all-new sedan, which was previewed last month as a concept at the 2011 Shanghai Auto Show, is slated to arrive at dealers in spring 2012, most likely as a 2013 model.

The engine images first appeared on the fansite M5board.com. The biturbo V8, sans the usual production-spec plastic shrouds and covers, appears to completely fill up the car's engine compartment.

Another fansite, bmwblog.com, says the modified S63 engine in the new M5 — a version of the same power plant in the X5 M and X6 M — will produce around 578 horsepower and 530 pound-feet of torque. In comparison, the normally aspirated V10 that powered the 2010 M5 was rated at 500 hp and 383 lb-ft.

BMW said the V8 in the new M5 will be mated to a seven-speed M dual-clutch transmission with Drivelogic (a six-speed manual will likely be available as an option in the U.S.). European press reports have speculated the car will accelerate from zero to 60 in less than 4.4 seconds, with top speed electronically limited (in some markets) to 155 mph.

BMW also said the new V8 will be fitted with an automatic stop-start function that will help trim fuel consumption and emissions by 25 percent or more. A limited-slip differential will also be part of the package.

The new M5 gets a tuned and lowered M suspension and M-specific steering, as well as unique 20-inch forged alloy wheels shod with 265/35ZR20 tires. The car also features a new Active M rear differential with variable torque split.

Official images of the fourth-generation M5 (code name: F10) will be released in June, and the car will make its formal public debut in September at the 2011 Frankfurt Auto Show. Rumored price tag will start from around $100,000.

Source: Inside Line