Various reports suggest that the current-generation Mercedes S63 AMG will be the last model powered by the company's M157 5.5-liter, twin-turbo V-8 engine.This engine was unveiled in 2010 to replacement the previous naturally aspirated M156 6.2-liter, V-8. According to AMG chief Tobias Moers, the relatively young 5.5-liter has reached its output limits, so it cannot exceed 577 horsepower and 664 pound-feet of torque without threatening reliability.

Of course, the engine will see use in the upcoming S63 AMG->ke359 coupe and convertible variants, and in every other 63 AMG models in 2014, but you shouldn't expect to see it in any next-gen AMG ->ke187 models, like the next generation E-Class set to arrive in 2016.

While there are no indication on what engine will replace the 5.5-liter, V-8 engine, AMG is currently developing a new 4.0-liter engine by essentially bonding two of its 2.0-liter, four-cylinder turbo engines together. This new engine will see its first action in the AMG variant of the upcoming C-Class and the upcoming SLC.

There is the possibility of the 5.5-liter engine being replaced by a hybridized version this new 4.0-liter, V-8 engine, but this is pure speculation at this point.

Click past the jump to read more about the 2014 Mercedes S63 AMG.

2014 Mercedes S63 AMG

Mercedes unveiled the new S63 AMG at the 2013 Frankfurt Motor Show and will put it on sale on the U.S. market in November.

The model is powered by an updated 5.5-liter V-8 biturbo engine that delivers a total of 577 horsepower and 664 pound-feet of torque - an increase of 49 horsepower over the previous generation. For the first time, the new S63 AMG comes with 4MATIC all-wheel drive, which distributes 33 percent of the power to the front axle and 67 percent to the rear axle.

With this amount of power, the S63 AMG will sprint from 0 to 60 mph in just 3.9 seconds and up to a top speed of 186 mph.