Driving a concept car doesn't usually teach you anything. These high-dollar aesthetic exercises rarely carry real-deal connections to the road cars they will one day spawn. But the Mercedes-Benz Vision EQXX is no normal concept car; rather, it's an engineering test bed for next-generation EV technologies, and after some time behind the wheel, these developments feel pretty much ready for prime time.
My drive in the Vision EQXX has a singular purpose: maximum efficiency. I have a 10-mile stretch of Mercedes-Benz's Immendingen test road ahead of me, and I must drive as efficiently as possible as I attempt to meet or beat the numbers set by Mercedes' own engineers.
Slinking into the front seat, I'm hit with a mix of familiar and unfamiliar. There's plenty of forward visibility, but rearward is a different story; solar panels occupy the whole roof, so there is no rear glass whatsoever, nor is there a rearview mirror. Traditional side mirrors are present, which the engineers told me was a conscious decision because digital side mirrors add too much weight and electrical consumption. All these sacrifices pay off with an extremely slippery drag coefficient of 0.17, which means it cuts through the air better than a football.
Moving the all-too-familiar shift lever into Drive, it's time to depart. Without pounds upon pounds of sound deadening, the EQXX is surprisingly sprightly for an EV with a single motor on the rear axle producing 244 horsepower. It's a little noisier than your average Merc, sure, but it's a sacrifice I'm willing to accept given how it's meant to be used. High power output is the enemy of efficiency, though, so one good squeeze of the right pedal is all I give the EQXX before I settle into the hypermiling mindset.
The roads encircling Mercedes' Immendingen test track feature plenty of shifting speed limits and hills. Some EV owners are content to leave regenerative braking on the highest setting and stay there, and while recuperation is a good way to boost efficiency, it can be a detriment when scrubbed speed needs to be replaced. The EQXX features three regenerative braking levels and a freewheeling mode, and the latter is key. On downhill segments, freewheeling builds speed that I use to stay throttle-free for longer stretches of time. When the speed limit drops, then it's smart to turn on the regeneration and scoop up a few of those electrons that would otherwise go unused. Given the EQXX's slippery shape and powertrain programmed for efficiency, this car builds speed quickly while going downhill.
All the weight in the EQXX is situated nice and low in the body, so the car is surprisingly fun in turns. The low-rolling-resistance tires produce a decent amount of grip, which is nice, since they aren't exactly engineered with fun in mind. As my route continues, I get more comfortable with the car's actions and I stop scrubbing speed for turns entirely, reducing reliance on the powertrain even further. The only time I ever press the brake pedal itself is when a Mercedes engineer in an unrelated test vehicle enters a roundabout before I do. As much as I want to maximize efficiency, I also want to finish my route with an unscathed one-of-one development prototype.
Whenever curiosity gets the best of me on long stretches of road without traffic, I take a glance at the 47.5-inch display spanning the width of the dashboard. This car runs its own unique infotainment system that's devoted to explaining how and why the car is working to be efficient. Airflow diagrams point out wind speed and direction while displaying the status of its active front shutter and extendable rear diffuser. Another page shows where the sun is positioned relative to the solar panels. My favorite screen shows a variety of speeds above and below mine and how changing my speed will affect my expected route efficiency.
My feet are far from being the only arbiter of efficiency in the EQXX. So many pieces are hard at work in areas that you cannot see or may not think about. Under the body, the battery is cooled with air, rather than liquid and its energy-thirsty pumps. The 100-kWh battery itself has a revised anode chemistry that improves its energy density. The rear floor is the single largest piece of cast aluminum the automaker uses in any vehicle, providing crash stiffness while keeping weight low. The car's rear track is thinner than the front, further boosting its ability to slice through the air.
Sustainability is important in the EQXX, because it represents efficiency improvements in building the car. This wild-ass interior uses several interesting and sustainable materials, whether it's the mycelium in the seat cushions, the bamboo fiber in the shag carpeting, the recycled PET bottles in the floor and door trim or the vegan silk in the door pulls.
As I freewheel my way down the hill, back to where I started, Mercedes-Benz's engineers already have answers for how efficiently I'm driving. Using telemetry pulled straight from the vehicle, I average 8.2 kilowatt-hours per 100 kilometers, which means I could see up to 1,219 km (757 miles) on a single charge. That's only a hair under what Mercedes engineers used as the benchmark for the day's activities, and it's about on par with the EQXX's most recent jaunt from Stuttgart to Silverstone. For those of you used to American EV metrics, I manage 7.57 miles per kWh, or about double that of today's most efficient EVs.
That's bloody impressive, but it won't remain the stuff of research laboratories for long. The next generation of Mercedes-Benz EVs will take the lessons learned in the EQXX and adapt them to production vehicles, giving buyers better efficiency without adding layers upon layers of complexity. And you won't even need to turn the air conditioning down.
Editors' note: Travel costs related to this story were covered by the manufacturer, which is common in the auto industry. The judgments and opinions of CNET Cars' staff are our own and we do not accept paid editorial content.