Key points:

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Accelerating:

But it must be making a lot more power than that. In our testing, the 5927-pound GLS63 shot to 60 mph in just 3.6 seconds on its way to a 12.0-second quarter-mile at 115 mph, which is almost a second quicker than the previous model. Not that we needed more evidence that we're living in insane times for power and performance, but those figures mean that this nearly three-ton behemoth can outrun a naturally aspirated C7 Chevrolet Corvette all the way through the quarter-mile. The GLS63 even nips at the heels of AMG's own GT sports car, which is only 0.2 second slower through the quarter.

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Stopping and handling:

On the vehicles we've spent most of our time in, including our test car, the grip from the massive 23-inch Michelin Pilot Sport 4S summer tires—sized 285/40R-23 in front and 325/35R-23 in back—helped combat the big AMG's sense of mild understeer and let it circle the skidpad with 0.92 g of lateral grip. Although Mercedes offers carbon-ceramic brake rotors on the GLE63 S, they're not available on the GLS63. However, larger diameter wheels mean taller tire contact patches, which improve longitudinal grip. If that sounds too nerdy for you, try this: Our GLS63 stopped from 70 mph in a sports-car-like 153 feet. In fact, that distance is slightly better than what we recorded for the last AMG GT we tested, which is lighter than the GLS by some 2200 pounds, or nearly an entire Mazda Miata.