NICE, France – The first Mercedes-Benz electric car to drive more than 1,000 kilometers on public roads without stopping to recharge brought Jasmin Eichler to tears. It’s rare for someone in the car industry to really choke when they announce a new technical achievement, but Eichler, director of future technologies for Mercedes-Benz AG, without a doubt, put all her heart into the Vision EQXX, which has a brash plan. went on to achieve success in about two years.
The journey, called MissionXX, ended up being 1008 km (626 miles) from Sindelfingen, Germany, to Cassis, France. Along the way, it consumed only 14 kilowatt hours of energy per 100 miles. In comparison, the most efficient EV listed on the EPA website, the Tesla Model 3 Standard Range Plus, requires 24 kWh to travel 100 miles. That is an immense difference.
It was reached through rain and shine, through construction traffic and free-flowing highway miles—in other words, perfectly normal conditions—yet it arrived with enough energy left for another 143 miles or so. Mercedes won’t say exactly how big the brand new battery pack in the EQXX is, just that it has “nearly 100 kWh of usable energy” and has an exceptional energy density of more than 400 watt-hours per liter.
Eichler says this highly efficient battery exemplifies there are right and wrong ways to build a 1,000-mile electric car.
“The 1,000 kilometers itself could probably be done by anyone,” she said, adding that engineers could logically solve the problem by throwing enough cells into the battery to reach that distance and calling it a day. Instead, the MissionXX team went after every possible efficiency gain in an EV that could potentially also look like someone’s daily driver. Because the real goal of this mission was not just the distance target, but to achieve an efficiency level of less than 10 kWh per 100 km.
To do that, it’s best to start with aerodynamics, as they are vital for efficiency. According to Teddy Woll, head of aerodynamics at Mercedes-Benz, nearly two-thirds (62%) of the energy in the battery is required to expel air out of the way. Another 20% is used to overcome rolling resistance, and other factors account for the final 18%.
In the end, Woll’s team reduced the drag coefficient of the EQXX to 0.17 – far more than the smoothest car on the market today, the Mercedes EQS, which goes through the air with a CD of 0.20. The Tesla Model S is always slightly behind 0.201. This achievement is all the more impressive because Mercedes wanted to keep the car as close as possible to the “normal” appearance and therefore free of certain aerodynamic tricks, such as the rear wheel spatter used on earlier ultra-efficient cars such as the GM EV1 or VW XL1 (they accounted for a cD of 0.19).
Instead, the team used 20-inch magnesium wheels that are large and narrow and minimize wind resistance with lightweight aero covers. Bridgestone even designed custom Turanza Eco tires with ultra-low rolling resistance for the EQXX, with the lettering on the sidewall barely protruding from the surface. The underside, like many EVs, has been made as flat as possible, but the Vision EQXX can increase that area by about 20cm with an automatic rear diffuser that moves both down and out depending on driving speeds and other conditions. That’s enough for a gain of 0.01 in cd, meaning it was worth spending the extra weight of the system, according to Woll.
Lightweight was also important from the start, encouraging the creation of new technologies and reinventing old ones. It was also a process that never stopped: In the three months between the unveiling of the EQXX at CES in January and its 1,008-mile drive in April, engineers removed an additional 88 pounds from the vehicle.
“It was kind of, internally, an ‘Oh, shit’ moment,” Eichler said of the reveal. “We were like, ‘Oh my God, now we have to do it.’ And I think that was kind of when we really stepped it up.”
Her team also knew that every little bit helps, and eventually grouped the car’s technologies and components into three general bins: production car parts, fanciful “what if” items (which was possible in part because Mission XX, in fact, had no real budget cap. ) and then the most important category: high-efficiency technologies that may soon be found on production models.
For example, on the roof, solar panels supply energy to the non-traction electrical components of the car: the screen, HVAC, windshield wipers, and the like. By allowing some parts of the car to run on solar energy – these can of course also be fed by the battery at night – the solar panels provide an extra range of 25 kilometers.
Then there was the issue of battery cooling. There has long been a debate in the EV world about whether active or passive cooling is best for an EV battery. In the Vision EQXX, Mercedes has opted for a predominantly passive cooling solution, which it claims adds about 2% of the range because it is the most aerodynamic solution. However, active on-demand cooling of the powertrain still occurs when hatches on the front of the vehicle open to allow air to flow around the battery and then to exhausts in the hood.
Future concepts for sustainable materials that can be used in production cars dominate the interior of the Vision EQXX. On the floor is a deep-pile carpet made of bamboo fibres. The seats have built-in speakers that are held in place with 3D-printed UBQ thermoplastics made from household waste. There is also Dinamica microfiber made from recycled clothing and PET bottles, and components grown from mushrooms.
There were always two people in the car during the ride, but with a maximum weight of 198 pounds for the driver. The back doors won’t open. And NVH was not a top priority. This is not a quiet car on the same level as other luxury EVs: there are light knocks and you can really hear the regenerative brakes intervene at high levels. The seats aren’t exactly plush either, but the drivetrain team was made up of MissionXX engineers, not professional drivers, so they knew what they were getting into. The German engineering firm TüV Süd was involved during the ride to prove that all 1,008 kilometers were indeed driven without charging.
During a 30-minute ride in the Vision EQXX – Mercedes had no intention of letting journalists drive such an insanely expensive vehicle on public roads – the feeling of all these technologies coming together showed how valuable a moonshot mission like this could be. The car easily covered the short urban route in Nice, but there wasn’t much to like in terms of acceleration or handling. The EQXX seemed capable enough, but an enhanced riding experience isn’t the point here. On the 1000km run, the team stayed under the speed limit, they said, and the car is limited to a top speed of 140km/h. Mercedes drivers probably won’t accept those kinds of restrictions in the real world, but this mission was based on kWH-per-km rather than km-per-hour.
It gets really, really exciting when Mercedes starts allocating its performance teams to the next MissionXX-type project. Anyone who has been behind the wheel of an AMG model knows that Mercedes can handle the handling. It now ups its efficiency skills to find the perfect mix between excitement when accelerating and letting the bladders decide when to stop for a break and not the state of charge.
That integration is coming. For now, it’s worth imagining the depth of Jasmin Eichler’s pride in bringing so many aspects of efficiency together, creating a truly great EV. This mission was a success. On to the next.