2015 Mercedes-Benz CLA45 AMG

The Mercedes-Benz CLA45 AMG is the range-topping, performance-focused model of the CLA-Class lineup. Closely related to the GLA45 AMG, the CLA45 boasts the world's most powerful regular-production four-cylinder engine and a lightweight, purpose-designed all-wheel drive system.

In the CLA45's engine bay lies a 2.0-liter four-cylinder engine that makes 355 horsepower and 332 lb-ft. of torque thanks in part to a turbocharger and high-tech engineering such as multiple spark ignition and multiple injection. The mill sends the CLA45 from zero to 60 mph in 4.5 seconds and on to a top that is electronically limited to 155 mph.

Hand-built, the engine is linked to a seven-speed dual-clutch automatic transmission that sends power to all four wheels via a new 4Matic all-wheel drive system designed specifically to be used in cars with a transversally-mounted engine. It uses a power take-off unit that is built directly into the gearbox and cooled by its oil to transfer power to the rear wheels. By eliminating the need for a separate transfer case, the number of moving components drops and the total of weight of the system is reduced.

The engine's torque is distributed between the front and rear wheels by an electrohydraulically-activated multi-disk clutch that is integrated into the rear axle. Although part of a very complex system, it works in roughly the same way as a basic single-disk clutch. When the clutch is disengaged, the vehicle is primarily driven by the front wheels; when it is engaged, the rear wheels wake from their slumber and help move the car. Engaging and disengaging the clutch takes mere milliseconds.

Like most performance cars, the CLA45 AMG comes with a stability control that offers variable degrees of intervention. During aggressive cornering, Curve Dynamic Assist applies a touch of braking to the inside rear when to act as a torque-vectoring system and improve turn-in.

Underneath, the CLA's four-link rear axle has been beefed up and its three-link front suspension has been modestly reconfigured for improved handling. The CLA45 AMG uses a specially-modified electric steering system.

Aggressive appearance
The CLA45 AMG looks more dynamic than the regular CLA thanks to a twin-blade grille, muscular bumpers front and back, an air diffuser that incorporates four rectangular exhaust tips and a slightly lowered ride height. Model-specific exterior colors, wheel designs and "Turbo" emblems on both front fenders finish off the look.

Life aboard
The CLA45's cabin is largely carried over from the regular CLA. Unabashedly designed to appeal to a young and trendy audience, the cockpit is characterized by aircraft-inspired round air vents surrounded by chrome bezels and a three-spoke multifunction steering wheel upholstered in leather.

Carbon fiber trim on the dash, two sport seats up front and an AMG-specific instrument cluster that includes a timer emphasize the performance-focused nature of the car.

A 5.8-inch color touch-screen that protrudes from the top of the center stack comes standard, and it can be upgraded to 7 inches by opting for the Multimedia package that adds Mercedes' COMAND system. Controlled by either buttons on the center stack or a voice recognition software, COMAND integrates the car's audio, hard drive-based navigation, climate control and connectivity functions into a single unit.

The touch screen also lets passengers control Mercedes' MBrace2 infotainment system, which runs cloud-based applications and provides on-the-go access to the internet. In addition to offering a wide array of concierge services, Mbrace2 comes with an application that lets smartphone-wielding owners lock or unlock the car from a distance and instantly find it in a parking lot.

Standard Bluetooth connectivity enables the driver to make hands-free phone calls and stream music. Other standard equipment includes rain-sensing wipers, A/C, power front seats with three-position memory and an electronic parking brake.

The list of options consists of Advanced Park Assist, a panoramic sunroof, Blind Spot Assist, heated front seats, burl and walnut trim for the dash and door panels, bi-xenon headlights, a Becker MAP PILOT navigation system, 18-inch twin-spoke alloy wheels and summer performance tires. Three option packages are also available.

Occupant safety
In addition to seven airbags, the CLA45 features a radar-based Collision Prevention Assist system that can warn the driver of potential accidents and, when necessary, automatically apply the brakes to prevent or mitigate the severity of a crash. The car also comes with Attention Assist, which provides audible and visual warnings if it senses that the driver is drowsy.

Key competitors
The Mercedes-Benz CLA45 AMG has very few direct competitors. The Audi S4 comes close in terms of power and price, but it is slightly bigger, heavier and slower in the sprint from zero to 60 mph.

Mercedes has gone to great lengths to avoid overlapping in its lineup but CLA45 AMG customers will undoubtedly be tempted to look at the C63 AMG, which offers considerably more power in a rear-wheel drive package for not much more money.