According to VIN information dug up by F30 Post, the upcoming M4 will not only adopt BMW's new naming strategy, but its newest-generation 3.0-liter inline-six cylinder engine as well. Previous rumors had hinted at a 3.3-liter displacement and up to 450 horsepower output.
Of course, the M4's speculated new engine is coded S55 rather than N55 as in the more ordinary F30-series cars, and its power output is raised to 416 horsepower (or 310 kW as stated in the VIN-decoded info). The power gains are thought to come from a new cylinder head and increased boost from the turbochargers.
At 416 horsepower, the M4's latest rumored output is very close to the current E90-series M3's 4.0-liter V-8 engine rating. With turbos driving that output, however, torque is expected to be about 100 pound-feet higher than the V-8's and it's likely to be available over a much greater rpm range, too. The current V-8's high-revving, peaky nature is engaging and thrilling to hear, but the new engine's proposed increase in area under the curve could result in markedly better performance.
Extra torque and more horsepower at any given rpm aren't the only expected improvements, however: the M4 is thought to be targeting the E46 M3's weight of about 3,400 pounds--a 300-plus-pound savings over the E90-series M3.