Its tragic destiny: to replace AMG’s 6.2 liter V8.
According to Car and Driver, AMG has confirmed reports that they are currently developing a 4.0 liter twin turbocharged V8 engine for future AMG vehicles—including the next-gen C-Class AMG and the SLS AMG's replacement. In case you're having difficulty reading between the lines here, that means it will replace the naturally aspirated 6.2 liter M156 and M159 V8s we've fallen in love with over the years.
The mainstream version of new 4.0 liter V8 headed for the next C-Class will be dubbed M177, and should produce somewhere between 460 and 500 horsepower in the C[whatever it's called] AMG of 2015 or so. (It'll likely also replace the naturally-aspirated 5.5 liter V8 called M152 that's solely used in the SLK55.) The SLS AMG replacement's motor will be known as the M178, and thanks to a fair share of unique parts (kind of like the changes AMG made for the SLS's motor, we assume), the M178 should crank out around 590-600 horsepower.
Considering the wide range of power the M177/M178 can be tuned to produce, don't be surprised to see it slowly replace the 5.5 liter twin-turbo M157 used in most of AMG's current lineup. The new motor will likely be much more fuel-efficient than the outgoing units, thus enabling Mercedes-Benz to keep selling ridiculously powerful sport sedans, gran turismos and sports cars even in the face of increasingly strict fuel economy regulations. One final thought, though: With AMGs first adding all-wheel-drive and then switching to a 4.0 liter twin turbo V8, how long until they slap a four-ring badge on there? [via Car and Driver]