Big News In Small Performance
I almost feel bad for any manufacturer that has a turbocharged four-cylinder-powered small car scheduled to be released within the next few years. Not only is the new 2014 Mercedes CLA45 AMG breaking new ground in small performance sedans, it will likely be the benchmark for the next generation. I say "almost" because with a base price of $48,350 and an expected transaction price closer to $55,000, other manufacturers might not see AMG's latest and greatest as direct competition.
The previous generation of A-Class would never have worked in the U.S. It wasn't much more than an average commuter car with a Mercedes interior. This new CLA is inspired, not to mention sexy, and will likely be a hit on our side of the Atlantic. It was these sexy lines that first attracted AMG to the idea of taking on the CLA. Once it became clear that the car would deliver in the driving department, the deal was set.
To begin with, AMG decided sticking with a four-cylinder was the only option. Although the architecture between the standard Mercedes and AMG is similar, the two share few parts. AMG starts with a proprietary block, head, and most hardware. Obviously the turbo, which provides 26 pounds of boost, is larger than the standard unit and requires an AMG-specific water-to-air charge-cooler. The pistons and crank are forged, with balancing and weight optimization said to be near racing level. The result is 355 hp and 332 lb-ft of torque. Although this will be the most powerful I-4 for sale in the U.S., the numbers aren't the most impressive part.
Through careful and near-obsessive engineering, the team at AMG has produced a turbocharged engine that delivers 177.5 hp per liter and develops full torque from 2250 to 5000 rpm. In practical terms, not only can it deliver a mountain of torque on demand, it can deliver the exact level of torque the driver requires. High-strung turbocharged engines generally supply torque as an all-or-nothing proposition, but this engine delivers levels of throttle modulation and response more fitting of a naturally aspirated mill, and it does it all while providing a ripping, GT race car-like sound track. Full-throttle acceleration opens up a valve in the exhaust, creating an angry, growling roar that crescendos with a load brap at every shift.
This dream of an engine feeds into a seven-speed dual-clutch transmission developed with Mercedes. Rolling away from the line, the transmission can be a little too aggressive and snatches the clutch a little too quickly, feeling like a manual transmission with a less-than-skilled driver on the right pedal. Once rolling, however, shifts are fast without being violent. On the roads around Hannover and the amazing Bilster Berg Race Track, the transmission never faltered. It offers three modes: Comfort, Sport, and Manual. Pulling either paddle in Comfort or Sport allows for Momentary Manual mode, which will hold a gear until the driver initiates a kick-down with the throttle pedal or an upshift is needed at the rev limiter. On the track, using Sport Mode plus Momentary Manual seemed to work best. Pulling a paddle to downshift going into tighter turns would get the car into the powerband and the computer seemed to pick upshift points just fine.
Those same tight corners showed the necessity of the CLA's all-wheel-drive system. This is still a front-wheel-drive-based system, and you will never confuse it for anything else, but it is still quite capable. AMG claims the system is up to 25 percent lighter than similar systems. Instead of a Haldex power unit hanging off the back of the transaxle, a clutch pack has been located on the rear differential housing for better weight distribution. The system can transfer up to 50 percent of drive torque to the rear tires. It's tied into the car's ESP and also uses steering input, yaw, and throttle level to determine how and when to transfer power.
Although AMG feels that the CLA's suspension is best in class, it wasn't up to the performance level of the powertrain. Like the base car, the AMG CLA uses a McPherson strut front and multilink rear, but that's where the similarities end. As you would expect, spring and damping rates are more aggressive, but AMG has also changed both static and kinematic geometry. The front spindles were designed with more static negative camber, but the lower ball joint pivot was lowered to add more kinematic camber and raise the roll axis. If you've been paying attention during the last couple of years, you will realize that suspension performance is all about bushings, and this car is no different. The durometer (a measure of hardness) of all the bushings is different from the standard car, and even the steering tie-rods feature stiffer bushings. The difference is immediately noticeable not only in the level and clarity of steering feel, but also in impacts on broken pavement. Impacts can be sharp in the AMG, though they stay short of harsh.
The standard wheel is an 18x8-inch split five-spoke design, while the optional 19x8-inch multi-spoke wheel is available in silver or dark grey. The 18-inch wheel uses a 235/40 tire, while the 19-inch uses a 235/35. Underneath those wheels are 4-piston calipers over 13.8-inch rotors in front and single-piston calipers over 13.0-inch rotors in the rear.
Mercedes gave us the better part of a day to lap the CLA45 around the track, plus a day and half of driving around the roads and autobahns around Hannover. On the road, the CLA45 feels small and agile -- not exactly what we've come to expect from Mercedes. While it certainly feels every bit the level of quality we expect of anything with the three-pointed star, it is immediately obvious this car uses a cab-forward, transverse-engine layout. The driving position is near ideal, and the seats and steering wheel are a DTM fan's dream. Rear headroom is compromised by the sloping roof, but on the upside, the trunk has plenty of space. Road noise is minimal and engine noise is fantastic.
The AMG genes really come out on the track. The little sedan's limits are easily approachable, even with the stability control completely defeated. If you aren't that confident about your own skills, AMG supplies a Sport mode that allows the car to slide around a bit before it pulls things back in with the brakes. Steering feel is some of the best I've experienced in a front/all-wheel-drive car, assistance is beautifully tuned, and turn-in is quick and linear. On-center resistance feels sure and positive—there is resistance immediately off center, and then it builds in the first few degrees. As you turn in a bit more, the resistance falls off some and the car starts to feel like it really wants to turn. At neutral throttle or with slight trail braking, the car rotates into corners around the center of the car. Turning in with the too much brake gives a decent amount of understeer. At the apex, the car keeps rotating until you pick up the throttle. If you are right at the limit, all four wheels drift out to the curb or, in off-camber or downhill turns, a little drift brings a stupid grin to your face.
The CLA45 may not seem like an ideal track-day weapon, but it was one of the most enjoyable cars I've had on the track in a long time. On the road, the mixture of luxury and performance make it a world-class sport sedan. AMG is projecting sales of roughly 10,000 units a year globally, with the U.S. being the number-one market. The BMW 135 and Audi S4 are named as the main competitors to the CLA45. We can see the 135, but the S4 seems to be bigger enough that it might not be cross-shopped. By next summer, Audi should have its new S3 for sale in the U.S., and although it will likely be slightly down on power, it will also be a bit down on base price. I'm really looking forward to the comparison.
2014 Mercedes Benz CLA45 AMG Specs
Base Price $48,350Vehicle Layout Front-engine, AWD, four-passenger, four-door sedan
Engine 2.0L/355-hp/332 lb-ft DOHC 16-valve turbo I-4
Transmission 7-speed dual clutch
Curb Weight 3300 lb (est)
Wheelbase 106.3
Length x Width x Height 171.6 x 70.1 x 55.8 in
0-60 mph 4.5 sec (mfr est)
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