Sethcedez

Hello everyone,

This week, my family is welcoming a 2017 CLS550 4MATIC into the family and I have to wonder, is the M278 in these really underrated, and if so, by how much? We've got the exact same engine in our 2017 GLS550 which is rated at 449hp/516lb-ft of torque and even that is supposedly underrated... I just want to know how much power these cars really make! Thanks.

wheatswake

Yes, the M278s are underrated. Think some have achieved 700hp+. I know there are tunes ($1500+) that will get you another 100+hp alone. I would address all the known weak points, old/brittle plastic lines/rubber hoses, seals (oil/coolant cooler for example), grounds, oil leaks, compression test, etc. before modding. Have a known solid foundation before building on it. I have done mods not to create more power but to have a reliable engine. If more power comes with those minor mods, fine with me. Just having intake airbox spacers, to let the engine breath better, I think makes a difference in cooling capacity. I don't track my 2x M278s, so the 409hp/449hp is fine for me. Hope this helps some.

DigitalDisaster

I wouldn't say they are underrated, the increases in later models result from improvements and tuning. The M278 reponds well to tuning - my '13 CLS550 has a Weistech Engineering ECU tune and produces 540 HP/715 Ft Lbs torque which really transformed this car. Add downpipes for even more power : )