The updated Mercedes-AMG E63 S saloon and estate made their big debuts a few days ago, adopting the usual array of mid-cycle updates. But behind the tweaked front and rear fascias, new headlights, and a revised steering wheel borrowed from the AMG GT 4-Door, the bits that made the last E63 S such a dynamic stunner remain unchanged. Here's why.

While Mercedes could have easily rustled up some extra ponies as part of the 2021 update, there's a very good reason both the sedan and wagon retain 603 bhp and 627 lb-ft of torque at a time when other AMG products are piling on the power. And the biggest is the existence of the GT63S 4-Door, which features the same twin-turbocharged 4.0-litre V8 as the E63, but with 630 bhp and 664 lb-ft of torque.

“To emphasize the driving capabilities, it wasn't just a case of pure numbers,” Mercedes-AMG Director of Overall Vehicle Development Drummond Jacoy told on a conference call with other media. “We were very happy with the engine size and driving characteristics. We have a car lineup, and above the E63, we have the GT63 S, and we don't want to have an overlap there, so we kept additional power exclusive to the GT63 S.”

Well, there you have it. But surely there was room for other improvements, perhaps via Mercedes-AMG's critically acclaimed EQ Boost system, right? The AMG GLE 63 features the 48-volt mild-hybrid rig to great effect alongside its twin-turbo 4.0-litre – that model packs an E63-matching 603 bhp and 627 lb-ft, but is largely free of turbo lag because of EQ Boost. As it turns out, the lack of the system on this generation comes down to packaging concerns.

“The E63 has specific characteristics. We want [launch control], we want very, very precise shifting,” Jacoy said. “To do that, we use an electromechanical clutch rather than a torque converter.”

Gallery: 2020 Mercedes-AMG E63 Estate

EQ Boost relies on a torque converter along with an integrated starter-generator (ISG). You can't have one without the other.

“We have package constraints, so we decided to stick with the original powertrain as it was set up. We just couldn't get the ISG in there.”

The absence of EQ Boost or even a big power increase might seem disappointing in a world where more power seems to be the plan every time a vehicle gets an update. But the reality is that, with a 3.2-second sprint to 60 and a limited 186-mile-per-hour top speed, the E63 is pretty damn good without the extra oomph.

Gallery: 2020 Mercedes-AMG E 63 Saloon