Mercedes' Cheapest Car Is Getting Its Hottest Tech First, Not the S-Class

Move over, S-class. The Mercedes-Benz CLA-Class is poised to vault from the bottom of the lineup to the pinnacle, at least in terms of powertrain tech, when the next-generation model goes on sale next year. The first model on the new Mercedes Modular Architecture (MMA) introduces an 800-volt battery pack that unlocks blazing fast charging, a two-speed transmission that optimizes electric motor efficiency, and a new hybrid powertrain that replaces the conventional gas engine. For a brief moment at least, Mercedes’ smallest and cheapest vehicle will take on the S-class’s role as the vanguard of technology.

It won’t last long. MMA will eventually spawn two small crossovers to replace today’s GLA and GLB/EQB, plus a shrunken G-Wagen. The 800-volt architecture and likely the two-speed EV transmission will also trickle up to the MB.EA architecture that will underpin the next-generation Mercedes mid- and full-size models such as the E-Class and the S-Class.

We still have some time before Mercedes pulls the cover off the production CLA, but we just spent a full day diving into all the details of what’ll be beneath the sheet metal. Between the CLA concept shown in 2023 and what we now know about the architecture and powertrain, it doesn’t take much imagination to fill in the gaps.

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Double the Voltage, 1.5 Times the Charging Fun

Electric CLAs sold in America will all be powered by 85kWh nickel-cobalt-manganese (NCM) lithium-ion battery packs that should achieve at least 466 miles of range on the forgiving European certification cycle. We predict our cars will show something closer to 350 miles on the window sticker. European customers also get the option of a 58-kWh lithium-iron-phosphate (LFP) battery in cheaper models.

Both packs contain 192 prismatic cells wired in series and packaged in four modules. The 800-volt NMC pack allows engineers to turn up the peak charging power from 170 to 205 kW in the 400-volt EQS and EQE to 320 kW in the CLA. Mercedes says a 10-minute charging session will deliver 186 miles of range with an average of 216 kW, but that’s also based on Europe’s WLTP test. Expect something more like 140 miles of range at American highway speeds after 10 minutes of charging, which would still make it one of the quickest charging EVs in MotorTrend testing. Mercedes also claims the pack can be zapped from 10 to 80 percent in under 22 minutes.

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The key to sustained high-power charging is keeping heat in check. It’s a problem that can’t be solved with bigger heat exchangers or by chilling the coolant. Instead, engineers had to reduce the internal resistance of the battery cells so the heat doesn’t accumulate in the first place. That involves making the electrodes thinner, which has the unhappy side effect of reducing energy density. The compromise that Mercedes engineers settled on gives the NMC cells an energy density of 680 watt-hours/liter, compared the to 620–650 watt-hours/liter for the cylindrical 4680 cells used in the Tesla Model Y and Cybertruck.

Speaking of Tesla, Mercedes tells us that U.S. market cars will come with the J1772 charging port for AC home charging and the Tesla-designed NACS charging port for DC fast charging. That's a strange, confusing solution for the coming switchover from the CCS fast-charging standard to Tesla's design. A Tesla home charger will plug into the NACS port but won't be able to charge the vehicle with alternating current. So despite having two ports on their cars, some CLA owners will inevitably have to carry two adapters, a CCS-to-NACS unit and a J1772-to-NACS adapter for plugging into Tesla destination chargers and home chargers.

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Why Two Gears Are Better Than One

Electricity is turned into motion through a 268-hp permanent-magnet rear motor and an optional 107-hp permanent-magnet front motor. The two-speed transmission integrated into the rear drive unit will make the CLA the fourth EV in the U.S. with a multispeed gearbox, following the Porsche Taycan[MF1] , the Audi E-tron GT, and the electric Mercedes-Benz G-Wagen.

The multispeed transmission has the same job in an EV as it does in a gas car. It allows the engine (or in this case electric motor) to operate at more efficient points over a wide range of road speeds. The CLA’s exact shift speed varies based on the accelerator pedal position, occurring along the dotted line in the graph below, with the CLA always upshifting into second by 68 mph. First gear features a 11.0:1 ratio and is engaged with a friction clutch for smooth shifts. The 5.0:1 second gear is selected with a dog clutch for better efficiency.

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The front motor runs through a single-speed transmission with an axle disconnect to improve efficiency during highway cruising. It sits high in the body—a consequence of designing the front subframe to carry a gas engine or an electric motor—with the half shafts running beneath the motor instead of in front of or behind it. Mercedes says the CLA will have a frunk, although a company rep didn’t clarify if that’s true for all models or only rear-drive versions without the front motor.

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Even the Gas Car Is Electrified

CLA buyers seeking the familiar comfort of gas stations will end up with a hybrid powertrain that combines a turbocharged 1.5-liter inline-four with a 48-volt motor-generator. Don’t be fooled by the motor’s low voltage. This isn’t the same system that’s found in today’s mild-hybrid Mercedes. Instead of an integrated starter-generator (ISG) connected to the engine through a belt, the CLA uses a motor built into the transmission. It makes up to 27 hp and 42 lb-ft of torque and is capable of driving the vehicle on electricity alone up to 62 mph. You won’t go far without firing the engine, though. The hybrid stores 1.3 kWh of electricity in a lithium-ion battery located under the floor and beneath the driver’s seat.

The engine, codenamed M252, is the newest member of Mercedes’ Family of Modular Engines (FAME), sharing the basic concept (but not the bore spacing) with the M256 3.0-liter inline-six and the M254 2.0-liter inline-four. In its most powerful form—the only version we’ll likely get in the U.S.—the engine alone makes 188 hp and 221 lb-ft of torque.

A twin-scroll turbocharger compresses the intake charge as high as 25.9 psi and forces it into an engine running the Miller cycle (early-closing intake valves) and a 12.0:1 compression ratio. It’s mapped for a perfectly stoichiometric 14.7-to-1 air-to-fuel ratio (also known as Lambda=1), an increasingly common tool used by engineers to meet tightening emissions regulations around the globe.

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Torque is sent to the front or all four wheels through a dual-clutch transmission equipped with a third clutch to disconnect the engine for pure electric driving. Why not just open both of the DCT’s clutches? The electric motor is geared to the transmission input shaft so it needs one of those two clutches to be closed to drive the wheels or recapture energy in any of the eight gears. While the engineers wouldn’t talk fuel economy numbers, they did divulge that they’re targeting diesel-like efficiency. We interpret that to mean highway fuel economy flirting with 40 mpg.

Cutting Out the Middle Man

If you’re anything like us, you’re probably wondering where the plug-in hybrid is. Don’t hold your breath. Turning the hybrid into a PHEV isn’t as simple as fitting a bigger battery. The motor would need to be more powerful, and thus larger, requiring a wholesale redesign of the transmission. Mercedes-Benz CTO Markus Schäfer says the costs are too high and the demand too low to justify building a CLA PHEV.

Within a few months we should have full specs and photos of the 2026 Mercedes-Benz CLA-Class. Even without the complete picture, we can say that the next-generation CLA looks like a technological leap compared to the basic budget-luxury vibe of the current car.