The rumours were unfortunately right. The C63's good old twin-turbo V8 is no more. This is the new Mercedes-AMG C63 S E and it's now a plug-in hybrid with a turbocharged 2-litre 4-cylinder engine. This is a big change because the C63 always had a V8. First a 6.2-litre naturally aspirated V8 in the W204 and then a a smaller twin-turbo 4-litre V8 in the later W205.
This engine is paired with a trick hybrid system that has a rear-mounted electric motor that operates through a two-speed transmission. The continuous power output of the electric motor is 94hp but it has a boost mode where it can provide 204hp that lasts for 10 seconds. But this new C63 is also hybrid and it has a battery with a capacity of 6.1kWh. That's enough for an electric-only range of 13km. If you happen to live close enough to your place of work, you won't burn a single drop of petrol.