Instrumented Test
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Warning: Weapons-grade four-cylinder underhood.
When Mercedes-Benz sends a model to AMG for high-performance finishing school, it’s hardly news. But until the CLA, nearly every car to make the trip to Affalterbach was packing an engine with a “V” cylinder layout. (The C30 five-cylinder diesel was the lone exemption, and it never made it stateside.) So when the power brokers at AMG began dropping not-so-subtle hints that they’d already had their way with the CLA’s inline four-cylinder powerplant, our curiosity was piqued. Would the result be a roguish, hair-triggered toy or a true CL63 AMG mini me, blending breathtaking power with Mercedes style and luxury?
Sound and Fury
If you’re expecting the deep-throated burble of its bigger AMG brethren on startup, you’ll be disappointed, as the CLA45’s exhaust note at idle is more akin to an air compressor kicking on in the neighbor’s garage than it is to a menacing V-8. But it would be a mistake to write it off on tone alone. AMG has managed to coax 355 horsepower and 332 lb-ft of torque from the 2.0-liter engine, much of it on the shoulders of a twin-scroll turbocharger capable of force-feeding the engine with up to a whopping 26.1-psi of boost. To make sure all the internals stay contained under all that duress, AMG uses a special crankshaft, pistons, and a sand-cast aluminum block, which is stronger than the die-cast unit found in the pedestrian CLA250. A dual-clutch seven-speed automatic transmission with three driving modes funnels the prodigious output through a standard all-wheel-drive system.
Thanks to a butterfly valve plumbed into the exhaust, the CLA45’s song begins to sound sweet around 3000 rpm and gets better as the revs climb. The power comes on early, pulling with the steady determination you’d expect from an engine that produces all 332 lb-ft of peak torque from 2250 to 5000 rpm; redline is 6700 rpm. Stay into it until it’s time to shift—either automatically or initiated by the steering-wheel paddles—and you’ll be rewarded with a downsized version of the familiar bruuuump that accompanies gear swaps in the bigger AMG models. Using launch control, which allows the engine to climb to 4000 rpm before storming off the line catapult-like, we posted 0–60 times of 4.2 seconds, and knocked off the quarter-mile in 12.8 with a trap speed of 110 mph.
Although it has a front-drive bias, torque is variable up to a 50/50 split, the distribution based on a laundry list of variables including vehicle speed, steering angle, gear selection, accelerator position, lateral and longitudinal acceleration, as well as any differences in wheel speed. All that processing power translates to confidence-inspiring stability on the straights and mild understeer in the corners, traits that had us wondering if the CLA45 might be too sterile in our first drive. We found the speed-sensitive electric power-steering assist to be accurate if not chatty.
Selecting Sport mode delays stability-control intervention and allows for increased torque at the rear axle, making it easier to counteract understeer with a heavy right foot. You’ll be left to your own devices when the stability control is defeated entirely—in the CLA45, “off” truly means off—except during braking; AMG has granted the stability control a Hail Mary feature of sorts that reactivates stability control whenever your foot is heavy on the slow pedal.
Specifications
VEHICLE TYPE: front engine, 4-wheel-drive, 5-passenger, 4-door sedan
PRICE AS TESTED: $58,845 (base price: $48,375)
ENGINE TYPE: turbocharged and intercooled DOHC 16-valve, inline-4, aluminum block and head, direct fuel injection
Displacement: 122 cu in, 1991 cc
Power: 335 hp @ 6000 rpm
Torque: 332 lb-ft @ 2250 rpm
TRANSMISSION: 7-speed dual-clutch automatic with manual shifting mode
DIMENSIONS:
Wheelbase: 106.3 in
Length: 184.7 in
Width: 70.0 in Height: 55.74 in
Curb weight: 3619 lb
C/D TEST RESULTS:
Zero to 60 mph: 4.2 sec
Zero to 100 mph: 10.6 sec
Zero to 120 mph: 15.9 sec
Rolling start, 5–60 mph: 5.7 sec
Top gear, 30–50 mph: 3.7 sec
Top gear, 50–70 mph: 3.4 sec
Standing ¼-mile: 12.8 sec @ 110 mph
Top speed (gear-limited): 158 mph
Braking, 70–0 mph: 152 ft
Roadholding, 300-ft-dia skidpad*: 0.94g
FUEL ECONOMY:
EPA city/highway (C/D est): 19/27 mpg
C/D observed: 22 mpg
*Stability-control-inhibited
Continued…