2021 Mercedes-AMG CLS 53 Performance

It's not the fastest AMG you can buy, but the AMG CLS 53 will be quick enough for most. It can reach 60 mph in only 4.3 seconds before surging on to a limited top speed of 130 mph. With summer tires, the top speed increases to 155 mph. Like the Audi S7, the CLS 53 benefits from an all-wheel-drive system but the CLS 53 is marginally faster, as the S7 takes 4.5 seconds for the benchmark 0-60 sprint. This is despite the fact that the Mercedes is less powerful. With a 3.0-liter six-cylinder engine and EQ Boost, the CLS 53 generates 429 horsepower and 384 lb-ft of torque. It's not just a good on-paper showing, as the CLS 53 impresses with the effortlessness of its power delivery. This powertrain may lack the character of a burly V8, but for its combination of potent performance and efficiency, it's hard to beat.

Slotting in above the less powerful CLS 450, the 2021 AMG CLS 53 combines a 3.0-liter inline-six turbocharged engine with EQ Boost and an electric auxiliary compressor. This integrated electric motor system assists the gas engine for brief periods, providing up to 21 hp and 184 lb-ft of torque. Peak outputs are 429 hp and 384 lb-ft of torque. Merc's Performance 4Matic+ all-wheel-drive system and an AMG Speedshift TCT nine-speed automatic transmission are standard.

At higher revs, the gas engine continues to spin smoothly and doesn't run out of power, while lower down, the mild-hybrid system endows the CLS 53 with an instant surge of torque. This large sedan makes quick getaways easy and passing slower traffic on the highway is an almost subconscious thought. The smooth-shifting transmission is equally adept, fading into the background when at a cruise but coming into its own when quick shifts are demanded under hard acceleration. It's a remarkably capable powertrain with no discernable flaws.

The benefit of the EQ Boost system comes into play nicely here. Its EPA-rated gas mileage figures work out to 21/26/23 mpg city/highway/combined, not too far off the 25 mpg mixed mileage figure of the less powerful CLS 450 which we review separately. Overall, the CLS 53 bests the Audi S7, which returns 18/28/22 mpg. In the city, the Mercedes is notably more efficient. With its 21.1-gallon gas tank, expect the CLS 53 to return around 485 miles per tankful in mixed driving conditions.