Mercedes-AMG GLS 63 and GLE 63 S Get a 603-HP V-8Mercedes-AMGMercedes-AMG works its magic on the GLE and GLS's twin-turbo 4.0-liter V-8, upping output from 530 horsepower to 603 horsepower.An active exhaust system broadcasts the V-8's flat-plane-crank sound that is unusual for an SUV.Mercedes-AMG claims a zero-to-60-mph time of 3.6 seconds for the GLE63 S and 3.9 seconds for the GLS63.For a while, it looked like the V-8 engine was quietly departing the product plans at Mercedes-Benz. The C63 got a four-cylinder, the G550 traded its eight for a six, and even the mighty Mercedes-AMG One is powered by a 1.6-liter V-6. But the mood is shifting, as evidenced by the new M177 Evo that powers the 2027 versions of the Mercedes-AMG GLE63 S and Mercedes-AMG GLS63. The M177 is a 4.0-liter V-8 with twin turbochargers, a flat-plane crankshaft, and AMG-appropriate output: 603 horsepower and 627 pound-feet of torque. There is a hybrid component, but only in the form of an integrated starter-generator that bolsters low-rpm response with 23 hp and 151 pound-feet.Mercedes-AMGMercedes-AMG claims a zero-to-60-mph time of 3.6 seconds for the GLE and 3.9 seconds for the three-row GLS. We expect they'll both be a few ticks quicker, given that we saw a 3.6-second run to 60 mph from a 2021 GLS63 and a 3.4-second sprint from a 2021 GLE63 S. Those times should remain the same, given that the V-8's output hasn't changed despite its new flat-plane crankshaft, a setup commonly associated with screaming supercar engines. In fact, the flat-plane M177 Evo makes its peak power at lower rpm than the former cross-plane version. Those 2021 AMGs hit peak horsepower at 6500 rpm, while the 2027 models make their 603 horses from 5500 rpm to 6100 rpm. So why the new crank? Benz told us that it's more about meeting emissions goals than enabling high-rpm breathing.Mercedes-AMGIn typical AMG fashion, the hot-rod GLS and GLE get some chassis upgrades and cosmetic embellishments to comport with the performance status of these big luxury SUVs. An electronic locking rear differential puts the power down without need for brake-based intervention, and AMG Ride Control+ suspension uses air springs and adaptive dampers to offer a (relatively) cushy ride in Comfort mode or locked-down body control in Sport or Sport+. The system's active anti-roll function squelches body roll, and AMG claims it can allow for more limber suspension articulation in those off-road situations that GLS owners are always getting into. If a GLE or GLS driver needs a bit of extra ground clearance, for example, the air springs can raise the ride height by 0.8 inch. More on-brand, the body can also hunker down 0.4 inch in the sporty drive modes or when driving faster than 75 mph in Comfort mode.AdvertisementAdvertisementAs for aesthetics, the 2027 SUVs get the new AMG grille—for better or worse—and there's a range of festive color options available from the Manufaktur program. We'll take the Yacht Blue interior and Moonlight White Magno exterior, please.Mercedes-AMG hasn't released pricing, but the 2026 models started beyond $130,000 and $150,000 for the GLE and GLS, respectively, and we don't expect they're getting any cheaper. Both models will start arriving at dealers this fall.➡️ Skip the lot. Let Car and Driver help you find your next car.Shop New Cars Shop Used CarsYou Might Also LikeGift Guide: Best Ride-On Electric Cars for KidsFuture Cars Worth Waiting For: 2025–2029