we don’t have all the details but we know 2025 E63 will:
1 - have P3 layout
2 - it will have an Inline 6 engine, so M256
and when you combine those with W214 body
you get a thoroughly modern performance hybrid.
next i will talk about why i think E63 specifically is the sweet spot and not S63 or C63 …
well first of all E class ( and BMW 5 Series ) are the sweet spot regardless of drivetrain choice.
C class is a punishment box - i had to drive it for 3 years. and S class is a flex on wheels, and a boat ( though the only one i drove was from the 80s ).
whereas E class is just a good car. I only drove one for about 2 weeks ( as a loaner from Mercedes while my C class was in a body shop ) but i loved it. and it was only an E300 so it was a 4 cylinder with 250 hp or so but it was a nice car - it just felt lovely. it didn’t have the cheap-ness of C300 but also it didn’t feel ponderous either like some S class might.
now apparently the new S63 E-Performance is NOT a boat but actually the new 5 Series that i drove ( it was the base model ) DID feel like a boat … and C class lately are all go-karts …
so just philosophically the E class seems to be the sweet spot between comfort and agility even before we get into engine options …
and i postulate that the Inline 6 in the E is likewise the sweet spot between the 4 in the C63 and the 8 in the S63 …
and i am NOT saying that because 6 is in between 4 and 8.
but rather M256 is the most modern Mercedes engine. it is a clean sheet design because Mercedes didn’t have Inline-6 engines in decades so when they decided to bring Inline-6 back they had to design one from scratch and as a result they came out with something ultra-modern.
it’s really the same as how when Volvo was dumped by Ford they had to reinvent themselves and came out with the drivetrain that i have in my S60. this PHEV system was WAY ahead of its time because it wasn’t just an iterative upgrade of an existing platform but a clean sheet forward-looking design.
in case of M256 the innovations are two:
1 - the fact it’s an inline-6 in the first place.
2 - the fact that it’s a “beltless” engine.
now BMW never stopped making I-6 engines but everybody else is now rediscovering them - both Mercedes, Jaguar and Mazda have created I-6 engines recently …
the benefits of I-6 in modern era are many.
1 - I-6 is inherently balanced whereas neither the 4, nor V8 are inherently balanced.
2 - modern engines are much more complex than older engines - they have things like turbos, intercoolers, variable valve timing and so on - and a V8 ( as well as V6 ) needs two sets of all of those - making them hideously expensive to make and maintain.
an Inline-6 allows automakers to get a handle on this exponentially increasing complexity by returning to a single cylinder bank, single turbo, single set of camshafts and so on …
with modern turbo and hybrid tech you no longer need a huge engine to make a car fast - so you don’t need a V8 anymore … but on other hand a 4 cylinder just simply lacks the finesse expected of a luxury car - 4 cylinder engines lack smoothness …
to even try to make a 4 cylinder somewhat smooth you need counter-balancing shafts which only add complexity and weight - but why bother when you can just use an inline-6 which is inherently balanced ?
so I-6 is just what the doctor ordered and that’s the reason they’re coming back in luxury products like Mercedes and Jaguar.
the M256 in particular is also installed in Aston Martins.
the other benefit of M256 ( beltless design ) is due to it being born as an electrified engine from the start …
M256 uses an ISG ( integrated starter generator ) and electric ( as opposed to belt driven ) accessories. by contrast both 4 and 8 cylinder engines from AMG still use belts as well as a belt driven Starter/Generator.
eliminating belts not only makes the engine quieter, smoother, more efficient and more reliable but the real benefit is the torque fill from the ISG …
compared to belt driven Starter/Generator
an Integrated Starter/Generator
is much stronger as it isn’t knee-capped by what the belt can handle …
the S63 E-Performance with the V8 doesn’t need torque fill because it inherently has torque from the V8 … but the C63 E-Performance suffers because even with electric turbo it doesn’t have enough low-end torque and the belt driven Starter/Generator is too weak too fill that missing low end …
however the E63 with M256 engine which features both ISG and electric supercharger ( in addition to regular turbo ) should be able to deliver the low end torque customers expect. if this wasn’t the case i suspect Aston Martin wouldn’t be buying this engine from AMG !
and it will deliver this torque from a simpler, more reliable and more efficient engine than the V8 in the S63 …
E63 is expected to have 700 hp - 500 from the M256 and 200 from P3 motor.
i actually think that E63 will make significant power from just ISG, which in other M256 applications makes only 20 hp ( but 180 lb ft torque ).
what is limiting the power of ISG in other applications ( like Mercedes S500 ) is that it runs on 48 Volts there … but in E63 it will run on 400 Volt architecture and will likely be able to deliver about 50 hp.
with about 250 hp coming from electrons the I-6 will only need to make about 450 hp to reach the target 700 hp needed to compete with BMW M5 …
450 hp from 3.0 liter using a combination of turbocharger and electric supercharger is easy peasy. combined with 180 lb of torque from ISG the power should be seamless from idle to redline.
actually this is very similar to what my Volvo S60 T8 has - it also has an ISG, Supercharger and Turbocharger and a rear motor made by Siemens. And Volvo came out with this system in 2015 whereas AMG will debut this in 2025 …
of course the AMG system is going to be better than the Volvo system … but Volvo still deserves a lot of credit here.
essentially the ISG will provide torque for the first 1,500 rpm or so, then from about 1,500 to 3,000 rpm the electric supercharger will provide the torque and from about 3,000 RPM the turbo will take over ensuring a seamless powerband …
then separately in the rear electric motor with 2-speed gearbox in he P3 hybrid system will also provide seamless power across all driving conditions …
with electric motor, gearbox, battery and power electronics all in the rear the E63 will have a perfect 50/50 weight distribution ( the C63 E-Performance is actually slightly heavier in the back than front now ! ! ! )
with essentially separate drivetrains front and back yet coupled mechanically through the propeller shaft you will have each one smoothing the other out like a flywheel but without overloading either transmission or the shaft …
essentially you should have a car that is almost as good as S63 E-Performance but for about $50,000 less and with better efficiency and reliability … with only the rear seat passengers truly feeling that $50,000 difference … for the driver it should feel almost as good ( minus V8 noise ).
everybody thinks the C63 E-Performance was ruined by the 4 cylinder engine … and to a certain extent it was …
but it was really the belt-driven Starter/Generator that ruined it …
or rather the combination of 4 cylinder, gigantic turbo and tiny belt driven Starter/Generator don’t work together
the other thing that doesn’t work in C63 E-performance is the punishing ride, which i also had in my C300 … Mercedes believes that C class customers should suffer to differentiate C class from the bigger brothers …
essentially i think E63 will address a lot of the issues with C63 without going into S63 price territory …
and this isn’t just the the argument to moderation logical fallacy
i explained to you that i am not just saying E63 is the best of the 3 because it is in the middle between C63 and S63, but because the M256 engine is the most modern of the 3 and the only one that has an ISG …
now it is NOT guaranteed that E63 is actually going to have an ISG or an electric supercharger but …
the E53 has been fully revealed already and makes 600 hp without even the 200 hp rear motor or the electric supercharger …
so Mercedes has all the tools they need to make E63 a killer vehicle.
with S63 the held back a bit - they could have milked that powertrain for a few hundred more hp but they felt they gave the customer enough …
with C63 they over-reached in the other direction - they pushed that 4 cylinder and belt driven starter/generator too far creating what is essentially an overpriced Mitsubishi Lancer Evolution / Subaru WRX STI.
with E63 though i feel like the amount of power that will be asked from that M256 is exactly the amount it was always meant to produce. it will neither be de-tuned like the V8 in S63 nor boosted into oblivion like the 4 cylinder in C63.
the downside is it will neither be a bargain like C63 nor a baller’s car with V8 rumble like S63
it will simply be a technically excellent vehicle
now you can also make the argument that the already-revealed E53 is already the sweet spot car you’re looking for
https://www.caranddriver.com/news/a60148268/2025-mercedes-amg-e53-hybrid-4matic-revealed/
but with all of the power coming through the same gearbox the shifts will be quite noticeable. i drove a similar drivetrain in BMW X5 50e and the weak point of that drivetrain was the transmission - there were very noticeable gaps in power between gears … essentially putting both the engine and motor through the same transmission is too much torque and inertia for that transmission - they just do it to save money.
traction motor in front is too much for transmission …
belt driven motor is not enough for torque fill …
ISG is ideal but is expensive to adopt to engines not designed for it … however M256 was designed with ISG from the start …
but if you want to have effective regenerative braking you need to have a separate motor in the back like in my Volvo that doesn’t have to go through 5 shifts every time you’re slowing down for a red light …
and with E63 you will finally have all the pieces of the puzzle assembled …
of course Porsche Panamera E-Hybrid is already good, because of the PDK transmission, but it is also very expensive because of the high-end platform shared with the Bentleys …
the Panamera E-Hybrid also has a hatch boot and seats that fold flat with the trunk floor - whereas the trunk floor in AMG P3 hybrids is anything but flat and cargo practicality can’t hold a candle to the Panamera …
Panamera also has Active-Ride and mostly aluminum chassis and V8 sound etc …
By all means if you can afford Panamera Turbo S E-Hybrid go for it …
but the E63 is going to offer similar drivetrain performance for about $50,000 less … with aforementioned compromises versus the Panamera …
the other difference between Panamera Turbo S E-Hybrid and AMG E63 E-Performance is that Panamera is a normal plug in hybrid that has range-optimized battery. you won’t get the best experience without plugging it in every night as the V8 is thirsty and the strategy is to keep it off by driving in EV.
the E63 will be more like a regular hybrid that will have a plug but won’t really require plugging in every night because the electric components in E-Performance are optimized more for power than range so even if you plug in you will barely get any EV range anyway.
with E53 the fuel saving is form having a smaller engine ( 3.0 liter versus 4.0 liter ) for same overall power ( about 700 hp ), rather than from keeping a giant engine off by driving in EV mode.
well, we don’t know those details yet. although C63 has only about 6 miles of EV range the S63 has a more meaningful EV range. battery tech is evolving all the time so we don’t know for sure how E63 battery will be optimized, but likely it will be for power over range.
for those who don’t need max performance there is already E53 with long EV range but i expect E63 to have a much faster shifting transmission unburdened by the inertia of large electric motor in the front, as well as more power and torque overall due to second motor in the rear and finally E63 should drive much smoother in EV mode with a dedicated EV transmission that doesn’t have to shift all the time. best of all the extra 100 hp or so will come without any weight penalty to the front axle.
basically i expect E63 to be a technically excellent car without the " if you have to ask you can’t afford it " price …
