Peter Palmer: 2020 Mercedes-AMG CLA 45: Compact Benz Packs A Mean Punch

2020 Mercedes-AMG CLA 45 debuts with the world’s most powerful four-cylinder.
The engine produces over 380 horsepower and sprints to 60 mph in just four seconds.
Expect the new Mercedes-AMG CLA 45 later this year, with pricing due close to that time.

The 2020 Mercedes-AMG CLA 45 is finally here. It’s essentially a compact sport-luxury car with the power and torque output of a muscle car. It carries the same design language as the larger CLS but is no bigger than a C-Class. In short, it’s a small little monster packing a mean punch. Over the next few minutes, we will take a look at the new Mercedes-AMG CLA 45.

And it’s only fitting we start with the engine.

Mercedes-AMG M139 Engine

The outgoing Mercedes-AMG CLA 45 is by no means a slow car. It came with the M133 engine producing 375 horsepower. However, if there’s one thing not so good with the old engine, it’s that it has a tendency to dump all its torque at lower engine speeds. Enter the new M139 engine. For starters, it’s the most powerful production four-cylinder in the world. In the 2020 Mercedes-AMG CLA 45, the motor is good for 382 horsepower and 354 lb-ft. of torque, a reasonable jump from the previous output. Quite honestly, that’s a lot of oomph from a humble 2.0-liter four-cylinder.

Mercedes-AMG claims a zero to 60 time of only four seconds while top speed is electronically-limited to 155 mph. The optional AMG Driver’s Package increases that to 168 mph (so order that). More importantly, the motor is tuned to behave like a naturally-aspirated mill. Peak torque arrives at 5,200 rpm while Mercedes claims instant shove from as low as 1,000 to 2,000 rpm. And here’s the bad news: the M139 engine is also available in S form with 415 horsepower and 369 lb-ft. of torque. Sounds good, right, but that version is only available in the Mercedes-AMG CLA 45 S, which incidentally won’t be coming to the good ole’ USA.

Why? We have no idea. But to be fair, 382 horsepower is still plentiful for what is really a smallish and compact Mercedes. But then again, really Mercedes? America is all about horsepower. We can handle it.

The 2020 Mercedes-AMG CLA 45 employs a lightweight aluminum plate bolted underneath the engine. Known as the “shearing plate,” it increases the front end’s torsional rigidity. Photo: MBUSA.

2020 Mercedes-AMG CLA 45: One Man, One Engine

It’s not easy being the most powerful four-cylinder engine in the world. Mercedes had to develop a high-tech production line in Affalterbach to make it a reality. And since we’re talking about an AMG motor versus a mass-produced mill, each M139 plant is built using the AMG principle of One Man, One Engine; meaning the engine is built by hand and by a single person from start to finish. Technicians utilize a barrage of intelligent power tools that record each individual torque application. It allows technicians to build the engine in utmost precision while monitoring each and every step in the process.

Because if you’re building the world’s most powerful four-cylinder engine, you don’t take any chances with ordinary hand tools.

With this method, AMG technicians position the turbocharger and the exhaust manifold at the rear of the engine (on the side of the firewall when viewed from behind). The intake system is then at the front. Mercedes-AMG says this configuration creates the flattest possible and most aerodynamically-advantageous design for the engine’s front area. Furthermore, the turbine housing divides into two flow passages running parallel to one another. The divided ducts in the exhaust manifold make it possible to feed the exhaust’s flow to the turbine separately. The design prevents the individual cylinders from influencing each other negatively during load cycles, which according to Mercedes-AMG, helps boost toque.

It sounds like space age stuff, but this is how Mercedes-AMG rolls.

In addition to oil and water, air is directed to the turbocharger to help keep it cool. The Mercedes-AMG CLA 45 also employs roller bearings on the shafts of the compressor and turbine to reduce mechanical friction. Photo: MBUSA.

Dual Water Pumps & Dual Injectors

A high-revving and high-output motor will usually require the cooling capacity of a small nuclear generator. With that in mind, Mercedes-AMG gave the M139 engine a set of dual water pumps. The first is a high-performance mechanical unit supplying coolant to the aluminum cylinder head. The second is an electric water pump that operates independently from the mechanical one. In fact, this pump stays running even if the motor is off. This ensures the crankcase is always cooled as efficiently and as quickly as possible.

The M139 engine uses two-stage fuel injection. In normal operation, the engine receives fuel from a set of piezo injectors operating at 2,900 psi. If you’re really pushing it, the motor engages the second set of fuel injectors (with solenoid valves) mounted in the intake manifold. The injectors operate at 97.2 psi and help the engine achieve the highest possible output.

Related: The Mercedes-AMG A 35 Sedan is a nemesis for Audi and BMW hot shoes.

2020 Mercedes-AMG CLA 45: Transmission Tech

The 2020 Mercedes-AMG CLA 45 makes good use of a new eight-speed dual-clutch automatic. Power transfers to all four wheels via a fully-variable, 4MATIC+ all-wheel drive system. The drivetrain offers two distinct advantages. First, it’s a rear-biased system to give the driver the feeling of being shoved from the back. Next, the rear axle differential features AMG Torque Control. The latter means torque is not only split between the front and rear wheels, but it can also alter the torque delivery between the left and right rear wheels.

The result of all this wizardry is sure-footed traction whether on the street or racetrack. Best of all, the drive torque is controlled by an electromechanical system – one which Mercedes claims has a faster response and is more refined than a similar electro-hydraulic unit. This also means the new Mercedes-AMG CLA 45 can be fitted with an optional Drift mode. In this setting, all the power is routed to the rear wheels so you can perform ludicrous, tail-sliding maneuvers in your compact luxury Mercedes-AMG.

2020 Mercedes-AMG CLA 45. Photo: MBUSA.

High-Performance Everything

Without a doubt, the 2020 Mercedes-AMG CLA 45 is a small car but a high performing one. It has a high-performance engine, transmission, and driveline – but it also needs a high-performance suspension. Mercedes obliges with a McPherson strut design in the front and a four-link rear with three transverse control arms and a single trailing arm. The AMG Ride Control adaptive damping system is optional.

If the Mercedes-AMG CLA 45 can go like the wind, it needs to stop on a dime as well. The car is fitted with four-piston monobloc fixed calipers on 13.8 x 1.3-inch discs at the front, while the rear gets a single-piston floating caliper on 13 x 0.9-inch brake discs. The calipers have a gray finish with white AMG lettering while the discs are internally-ventilated and perforated to dissipate heat and prevent fade.

The car also receives speed-sensitive, electro-mechanical power steering and an AMG exhaust. The latter utilizes a flap to alter the exhaust sound depending on the selected driving mode. Speaking of driving modes, the CLA 45 has six, ranging from comfort to sporty (and even a race mode!).

2020 Mercedes-AMG CLA 45 interior layout. Photo: MBUSA.

Sporting & Luxurious Interior

The highlight of the interior is the new MBUX infotainment system. It creates a closer connection between man and machine by using advanced artificial intelligence. The system responds to voice commands so you don’t need to take your hands off the wheel to change vehicle settings.

Drivers will settle into the contoured front seats trimmed in black MB-Tex and DINAMICA microfiber. The multi-function steering wheel is wrapped in Nappa leather while the gearshift paddles are milled from galvanized aluminum. Stainless steel pedals with rubber studs, black roof liner, and stainless steel front entry sills with AMG lettering complete the sporting theme.

Pricing & Availability

The 2020 Mercedes-AMG CLA 45 is everything you can ask for from a modern Mercedes. Deliveries begin in late 2019 with pricing to be announced closer to that time.

Alvin Reyes is the Associate Editor of Automoblog. He studied civil aviation, aeronautics, and accountancy in his younger years and is still very much smitten to his former Lancer GSR and Galant SS. He also likes fried chicken, music, and herbal medicine.