Exploring the Mercedes-Benz EQXX: A Breakthrough in Electric Vehicle Efficiency

Electric vehicles (EVs) often face criticisms for their limited range and slower recharge speeds compared to internal combustion engine (ICE) vehicles. This stems primarily from the significantly lower energy density of their batteries in relation to traditional fuel tanks.

There are two main strategies to enhance a vehicle's range. The first is to increase the capacity of the fuel tank, which is relatively simple and cost-effective for conventional cars, but challenging and expensive for EVs. The second strategy involves optimizing various aspects of the vehicle, including aerodynamics, rolling resistance, and weight reduction.

Mercedes-Benz's EQXX achieved 1,008 km on a single charge, with an energy consumption of 8.7 kWh/100 km and an average speed of 87 km/h. The company has managed to create a highly efficient vehicle without simply relying on a larger battery. Let’s explore the innovative approaches behind this feat.

Aerodynamics

Aerodynamic drag is the primary consumer of energy in any vehicle. While drag is minimal at speeds below 60 km/h, it becomes the most significant factor at typical highway speeds. The Mercedes-Benz EQXX boasts a drag coefficient (Cd) of 0.17 and a frontal area of 2.12 m2, resulting in a total drag area of just 0.36 m2—remarkably low. For comparison, the Mercedes-Benz EQS, one of today's most aerodynamically efficient vehicles, has a drag area that is 39% greater at 0.5 m2.

This achievement is the result of numerous targeted design measures. Its sleek waterdrop shape, a rear section that is 50mm narrower, on-demand aero cooling, an elongated tail, and a combination of active and passive aerodynamic features all contribute to its efficiency. The covered 20-inch wheels help to reduce aerodynamic drag, accounting for up to 25% of the total. At a typical highway speed of 130 km/h, the EQXX requires only 14 PS of power due to these aerodynamic enhancements—an outstandingly low figure.

Powertrain

Mercedes-Benz claims an impressive 95% efficiency from the powertrain, from battery to wheels. In this power flow, energy loss can occur at three key points: the power electronics, the motor, and the gearbox. To achieve this high level of efficiency, each component must exceed 98% efficiency—a benchmark that remains largely unachievable in the current mainstream automotive sector.

While specific details about the motor are limited, it is likely a synchronous, permanent magnet type. The high efficiency of the motor and power electronics results in minimal cooling requirements, allowing for an innovative on-demand cooling system that reduces both aerodynamic drag and power consumption. The motor can deliver a maximum of 180 kW (245 PS) and is estimated to produce around 400 Nm of torque.

Bodywork

To maximize efficiency, lightweight construction is essential. Although electric vehicles benefit from regenerative braking, which allows them to harness kinetic energy, the amount of regenerative energy recuperated during highway driving is minimal. The EQXX has an unladen weight of 1,755 kg, a remarkable achievement considering that its high-voltage battery alone weighs nearly 500 kg.

The EQXX uses advanced materials, including aluminum, martensitic steel, and carbon fiber reinforced plastic, while its wheels are crafted from forged magnesium. The introduction of aluminum brake discs, lighter than traditional steel options, is another innovation. These ultra-light components work in tandem to significantly reduce the car's unsprung mass, enhancing both acceleration and ride comfort. The design philosophy also extends inside the vehicle, where sustainable, lightweight materials are used throughout. Additionally, solar cells on the roof contribute up to 25 km of range for low-voltage needs, such as the infotainment system and LED headlights, which holds significance during record-chasing attempts.

High Voltage Battery

The EQXX's high-voltage battery features a net energy content of 100 kWh and weighs nearly 500 kg. Its cell-to-pack architecture eliminates the need for modules, while an air-cooled design and a carbon fiber top lid further enhance its low weight. Compared to the high-voltage battery in the EQS, it is 30% lighter and occupies 50% less volume.

This vehicle also introduces a groundbreaking >900V architecture, allowing for incredibly fast charging capabilities with compatible DC chargers, although this may not be fully realized due to the passive air cooling method employed. To increase electric power, one can either enhance voltage or current; opting for increased voltage is preferable to avoid weight and space penalties associated with thicker cables.

Moreover, Mercedes-Benz has utilized a different anode material for the EQXX, incorporating High-Silicon anodes that significantly boost the energy density to 200 Wh/kg, making it the world's most energy-dense high-voltage battery. The combination of a carbon fiber lid and air cooling facilitates fitting this advanced battery into a compact design.

The EQXX remains a concept vehicle; however, the technology and innovations showcased here are expected to influence future Mercedes-Benz production cars, marking significant progress in the establishment and expansion of e-mobility.