Ride in the Mercedes Megameter EV

Meet the most efficient Mercedes of all time: the Vision EQXX. On Tuesday, April 5, this experimental concept car traveled 626 miles – or 1,007 km, just over a megameter – from its birthplace in Stuttgart, Germany, to the 6,900-foot Gotthard pass in Switzerland. up to the Côte d’Azur on a single 100 kWh battery charge. The car averaged 56 mph strictly adhering to all speed limits, peaking at 87 mph on an unrestricted stretch of freeway. They made two 15-minute bio-break stops, arriving in Cassis having consumed only 88% of the battery with 87 miles of range remaining (certified by German TÜV authorities). We traveled to the Nice design center that crafted the exquisite EQXX to learn how this impressive feat was accomplished and to get a sense of how close the next EQC sedan could achieve similar results.

Prioritize efficiency efforts

The overarching goal set for the EQXX team was to achieve single-digit kWh/100 km consumption (9 kWh/100 km = 233 mpg-e). The Riviera Run produced an overrun of 8.7 kWh/100 km (241 mpg-e). The team prioritized its efforts in proportion to the forces acting on such a high-speed electric compact sedan: 62% of the energy expended goes to overcoming aerodynamic forces, 20% to overcoming vehicle weight and rolling resistance, and 18% goes to transmission losses.

Lowest drag without fender skirts

Aero was obviously the development team’s No. 1 priority, and wheels are a huge issue (front wheels typically create a third of a sedan’s aerodynamic drag). The easiest (and ugliest) way to fix this is to run the wheels into the body with skirts or gaiters, but the Nice team managed to minimize wheel drag with wheel covers very smooth non-vented, specifying tire sidewall contours and requiring all labeling to be carved into the rubber, not embossed on it, and inlaying the rear wheels nearly 2 inches from the fronts, setting them in” the shadow of the wind” of the front wheels. The considerable taper of the greenhouse plan view makes possible those sultry rear shoulders that mask this “design no” (it also benefits aero), but at a considerable cost to rear seat shoulder room.

The next biggest aerodynamic advancement (good for 0.01Cd) is the rear diffuser, which extends almost 8 inches and drops 3 degrees at speeds over 35mph to work with the rest of the sharp edge that surrounds the tail of the vehicle to manage airflow separation and minimize drag-inducing turbulence. The rest of the story is more conventional: smooth underbody and A-pillars, smaller and more aerodynamic mirrors, an underbody “cooling plate” that rejects heat directly to the air passing under the car, responding to the most of the vehicle’s cooling needs so the conventional radiator should only be used for climate control or extreme heat. This is fed through louvered openings in the lower grille which exhaust air through the hood vents. The end result: a drag coefficient of less than 0.17 and a frontal area of ​​2.10 square meters for a total drag reduction of 29% compared to the EQS sedan (0.20, 2.51 m²).

Weight gain

Mercedes says the EQXX tips the scales at 3,870 pounds, slightly less than the 3,902-pound single-motor Tesla Model 3 Long Range we weighed in 2017 with a smaller 75kWh pack. A more energy-dense battery that relies on passive cooling is partly to blame. At 1,091 pounds, including the single-box charger/controller, it weighs about the same as an actively cooled 75kWh pack of a Model 3. The body structure uses megacasting in the rear which, unlike that of the Tesla Model Y, features a “bionic design”. The team used ZBrush “digital sculpting” software (like Disney/Pixar used to render Shrek) to shape this megacast, along with the cast front shock towers, die-cast rear belt anchors, and aluminum 3D printed. wiper motor support. These parts feature metal only where mechanical stresses require it, with lightening holes where no stress flows. If necessary, these holes are covered with UBX polymer panels produced from post-consumer waste. There are also composite springs, a carbon fiber rear engine mount and aluminum brake rotors.

Motor/battery optimization and solar roof

Mercedes has yet to release full specs for the EQXX’s battery and motor, except to say they run at 900 volts to further reduce amperage, wiring size (and ground) and losses. overall system. The battery still uses nickel-manganese-cobalt chemistry using high-silicon anodes and is said to deliver 95% of the input power to propulsion (90 is more typical). The 241hp Mercedes-developed eATS 2.0-based engine uses a new stator winding leveraging Formula E technology that places more copper near the rotor for increased power and efficiency. The roof and rear window are covered with 19.4 square feet of 25% efficient photovoltaic panels meant to largely power the infotainment and other non-propulsion systems, extending the car’s range up to 16 miles. on a sunny day.

Ride with the EQXX

While engineering development vehicles developed from scratch in 18 months, this one seemed oddly ready for production. Its 47.5-inch 8K resolution pillar-to-pillar micro-LED (non-OLED) display delivered dazzling navigational information, with an intuitive interface and lag-free responsiveness. Five different data visualization technology screens displayed plenty of engineering and eco-coaching information in crisp player graphics. Sun incidence angle and wind direction are used to accurately predict solar energy gain, and aerodynamic effects, road gradient and traffic forecasts are used to estimate instantaneous range remaining throughout the journey.

And the navy blue and white interior design is a stunning concept car while demonstrating a host of new eco-friendly materials (carpet made from bamboo, vegan “leather” from cactus and mushroom materials, and textiles woven from faux silk e-coli products) today seem to meet luxury expectations. The noise and vibration level could use a tiny bit of work, but the suspension soaked up the bumps with reasonable comfort and the car cornered nice and flat. Performance seemed roughly on par with the single-motor Tesla 3. On the other hand, the low energy consumption and “personal listening” headrest speakers did not offer Burmester fidelity, the rear seat is ridiculously unusable, you have to hide under low door frames , and we couldn’t peek into the trunk.

Could the next C-Class be a megameter mileage master?

The EQXX is sized like the next MMA-architecture C-Class, but a production version won’t go as far over 100kWh. Simply raising the roof and widening the rear track and/or greenhouse enough to provide a competitive rear seat will erode much of the EQXX’s aero superiority. Engineers describe EQXX technology as one-third production-ready now, one-third coming soon, and one-third completely experimental. We wonder if non-vented wheels and aluminum rotors can pass braking durability tests in a production car. The passively cooled battery is limited to 100kW charging power, which may not be considered commercially sufficient. And finally, he has to lose a few more drag counts each to put gutters on the A-pillars and make the mirrors meet size and rain-shedding requirements. But we’ll call it a huge win if it looks at least a bit like this – inside and out – and goes 450 miles on 100kWh.