You're looking at the most powerful turbocharged four-cylinder production car engine in the world. It's called the M139 and it's a 2.0-litre Mercedes-AMG unit, that's a replacement for the M133 that used to be found in the A 45 hyper-hatch, among others. The M139 is a development of that engine, with many technical updates and engineering solutions, all of which mean it can develop 382hp/480Nm in its regular trim - still 1hp stronger than the old M133 mustered up at the end - but a goliath 416hp/500Nm as an 'S', which equates to 208hp-per-litre. Yowzer! This raises the intriguing prospect of there being A 45 and A 45 S models in the very near future, whereas previously the A 45 has just been a solo warrior. Expect the M139 to power the new A 45 machines soon, then, where it will sit above the existing 306hp A 35 in the line-up. After that, we'd be very surprised if the M139 didn't also make its way to the A-Class Saloon, the CLA, the CLA Shooting Brake and, eventually, whatever the replacement for the GLA 45 AMG might be. And probably the forthcoming and inevitable GLB, as well.
Matt Robinson - 8 Jun 2019
