Mercedes-AMG updates the GLE 63 and GLS 63 SUVs with a new flat-plane-crank, twin-turbo V8 as part of mid-life changes. The outgoing models use an earlier-generation V8, and the upgrade is intended to improve efficiency and the driving experience, including smoother power delivery and reduced vibration. The new engine features a motorsport-inspired flat-plane crankshaft and a revised cylinder firing order, along with updated components such as a reworked camshaft, upgraded fuel-injection system, and changes to air intake and exhaust ports. Output is quoted at 604bhp and 627 lb-ft from the V8 alone. A 48V mild-hybrid system with an integrated starter-generator adds up to 23bhp and helps smooth torque delivery. With the mild-hybrid system, both SUVs accelerate from 0–62 mph in under four seconds and share a 174 mph top speed. The update also brings other revisions, including refreshed styling elements (such as new front-end grilles and larger intakes), an adaptive suspension system with active roll stabilization, and an exhaust system with adjustable flaps. The GLS gains a rear axle locking system, and both cars receive driveline upgrades to handle the higher torque.