How Emissions Regulations Forced BMW To Give The M2 ...

The big news with the new BMW M2 Competition is its engine. The just-announced version of the smallest M car ditches the regular M2's engine in favor of a detuned version of the M3/M4 motor, and while it brings more power and torque, that's not why BMW opted to go this route. The new motor will actually help the M2 meet upcoming emissions regulations in Europe.

Car and Driver reports that making the outgoing M2's 365-hp straight-six comply with Europe's stricter regulations would've required significant reengineering. The simpler solution? Stick the 3.0-liter twin-turbo straight six used in the current M3 and M4 under the hood instead. That this engine offers 40 more hp and 63 more lb-ft of torque over the regular M2 is a happy coincidence.

The standard M2 uses a version of BMW's N55 turbocharged straight-six, an engine that first came to market in 2009. The M2, which will be replaced by the 405-hp M2 Competition when it hits dealers as a 2019 model, was one of the only BMW models to still use the N55, rather than the new B58 3.0-liter six that made its debut in the 340i back in 2016. This year, Europe is adopting the stricter Worldwide Harmonized Light Vehicle Test Procedure (WLTP) for emissions and fuel economy testing, which effectively regulates the M2's N55 out of existence in its current state.

The S55 engine of the BMW M2

The S55 3.0-liter twin-turbo inline six that powers the M3 and M4 is based on the N55, but heavily reengineered. Motoring Research reports that BMW recently reworked the S55 to meet WLTP standards, so it could continue using the engine in M applications. The current M3 will end production soon, since a new 3-Series is on its way, and the 2- and 4-Series will follow suit not long after. But until then, BMW wants to sell some M cars.

So instead of reworking two engines—the M2's N55 and the M4's S55—BMW figured it would be easier (and presumably cheaper) to just rework the S55 and use it in the M2 and M4. That means BMW can sell both cars for a little longer, while making European regulators happy.

It seems like a win-win because enthusiasts get a more-powerful M2 with a real M engine, and BMW gets a car it can actually sell.

Chris PerkinsFormer Senior Reporter

A car enthusiast since childhood, Chris Perkins served as Road & Track's engineering nerd and Porsche apologist.