Range — and lots of it — is one of the holy grails of electric vehicles.
About two years ago, Mercedes-Benz management tasked top engineers with designing and producing the world's most efficient vehicle — an all-new electric sedan. The recipe was obvious: lightweight materials, aerodynamics and advanced battery materials and technology.
Mercedes-Benz introduced the Vision EQXX prototype this year at CES and is now demonstrating the coupelike car's real-world talent with long-distance treks across Europe. In one journey, from Stuttgart to Silverstone, England, where it hot-lapped the famous race circuit, the EQXX managed 747 miles on a single charge from a battery that stores slightly under 100 killowatt-hours. The average speed was 52 mph.
The feat, for a vehicle developed in just 18 months, has impressed analysts and journalists. And Mercedes says the demonstration bodes well for a lineup of electric vehicles coming on the near horizon that will draw on the EQXX's advances.
The smaller Vision EQXX delivers nearly the energy of the full-size Mercedes EQS sedan. And the battery pack is half the size and 30 percent lighter, Mercedes says.
To achieve more efficiency without increasing the battery's footprint, engineers increased the silicon content in the anode.
The battery featured in the Vision EQXX concept will make its way into a production vehicle around 2024, Mercedes-Benz officials have said.
And the automaker could bring an EV with more than 620 miles of range to the market by mid-decade.
Mercedes invited journalists for a limited test drive of the Vision EQXX at the company's giant product development and test center in Immendingen, Germany. We've rounded up some of the reviews and feedback.
"Similar to the Mercedes-Benz EQ-Series, the Vision EQXX allows the driver to alter the regenerative force with the steering wheel-mounted paddles (the left paddle increases regeneration drag while the right paddle decreases it). The most robust mode ('D- -') allows effective 'one-pedal' driving. An adept driver focusing on efficiency will actively use the paddles while driving to recuperate inertial energy, thus minimizing the need to apply the mechanical brakes (where the energy is lost as heat).
"Acceleration is leisurely off the line by most automotive standards, yet it's quicker than the typical combustion-powered economy car. Moreover, power appears to come on stronger once the vehicle is rolling. My professionally calibrated derriere says there's a sweet spot between 35 and 65 mph where the electric motors feel particularly strong — perfect for maintaining cruising speeds up hills or long grades.
"The low drag coefficient drastically alters how the vehicle is driven in terms of accelerator usage. Lift off the pedal, and the Vision EQXX glides along seemingly without resistance. If the road slopes downward, even a single degree, the vehicle will pick up speed. I noticed myself spending more time attempting to bleed off speed than trying to add speed — quite the opposite of how every other vehicle — electric or combustion — is driven. (Mercedes-Benz has not tested the vehicle's top speed, but my guess is that it will top an impressive 200 mph based on its low drag and power.)
"As is typical of most electric vehicles, the Vision EQXX boasts an impressively low center of gravity that considerably reduces body roll. Combined with its low mass, the driving dynamics feel delightfully energetic. As a result, the EV is agile, and its handling and responsiveness inspire confidence around corners and while negotiating traffic circles (even at elevated speeds). I was very proactive with the regeneration paddles, so I barely had to touch the brakes — driving the EQXX precisely as its engineers intended.
"The ride is best described as sporty – firm but never abusive. The low rolling resistance pneumatic tires are running 50 psi, which limits their fundamental cushioning ability. The suspension damping is not adjustable, and there's an absence of high-tech wizardry in engineered underpinnings (e.g., there is no 48-volt air suspension system like the S-Class), but the ride is comfortable — I'd drive it coast-to-coast across the United States without protest. On that note, the interior is surprisingly quiet at speed. Very little wind noise permeates the passenger cabin (the tires rolling over the asphalt aggregate is the loudest part of the ride).
"Mercedes' aerodynamics work is a combination of novel and familiar. In the latter category, an air curtain on the leading edge of the front wheel wells channels air to a breather on the trailing edge, reducing turbulence from the semi-flush magnesium rollers. The coke-bottle shape and excessively long tail are also familiar aerodynamic aids. But the EQXX benefits from other newer touches.
"For example, there are adaptive aerodynamic aids at both ends of the car, including a deployable rear diffuser that's as extreme as any dinner-table-sized rear wing. The rear track is 2.0 inches narrower than the front and keeps the back tires flush with the tapered rear end. Active shutters in the front fascia and a cooling plate in the underbody manage air flow without compromising cooling (supremely important with an air-cooled battery pack).
"This ability to coast almost endlessly was key to the EQXX's journeys from Germany to Cassis and Silverstone, and it was equally important during my test. I managed to eke out a consumption figure of just 7.4 kilowatt-hours per 100 kilometers (8.4 miles per kWh), beating the 7.9 kWh/100 km (7.9 miles/kWh) of Mercedes' test driver on the same stretch. That said, my average speed was about 5 kph (3 mph) lower than Mercedes' own test driver, so I'll call this contest a draw.
"Still, the EQXX was nearly three times more efficient than the production EVs I usually test. But even if I wasn't driving in such a pokey way, most of my colleagues recorded efficiency figures in the 8.0 to 8.5 kWh/100 km range (7.8 to 7.3 miles/kWh) while driving nearer the 49-kph average Mercedes saw along the same route. Those consumption figures aren't far off the 8.3 kWh/100 km Mercedes recorded driving from Stuttgart to Silverstone."
— Brandon Turkus, Motor1.com
"Perhaps most remarkable about this EQXX experiment is that the car isn't running on next-generation supercapacitors or solid-state batteries but instead on an optimized lithium-ion architecture rated at 920 volts. But the automaker considers its air-cooling of the module, as well as the battery management system and overall packaging, to be groundbreaking.
"With Formula 1 thinking, Mercedes' battery chemists squeezed the energy of the larger EQS all-electric sedan into the dimensions of a compact car. Relative to the EQS's 107.8-kWh battery, the pack in the EQXX is half the size and 30 percent lighter. The EQXX uses active cell balancing, which means drawing energy evenly from the cells, giving it greater stamina. The battery weighs 1,091 pounds, including its electronic controls.
"You're probably reading this wondering, why doesn't Mercedes just produce this EQXX that could rapidly accelerate the arrival of the tipping point for electric vehicles over conventional gasoline ones?
"It's not a simple answer. The engineers got to throw every weight-saving idea at this development project because Stuttgart's goal was a concept car that could drive at least 1000 km (621 miles) on a single charge, no matter the cost. Engineers rarely ever hear those last four words, so the ideas came pouring in.
"Many of the lightweight strategies got baked into the finished product, such as the ultra-thin solar roof, a subframe derived from Formula 1 racecars, a lightweight battery case, doors made of carbon- and glass-fiber reinforced plastics, aluminum brake discs (in place of cast steel), glass-fiber-reinforced plastic springs, and magnesium wheels wearing slim tires optimized for ultra-low rolling resistance rather than grip.
"With so much moonshot technology onboard, it's no surprise the development team hesitates to put a pricetag on this futuristic prototype. Think seven figures."
"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."
"With a drag coefficient of 0.17, the EQXX isn't the most aerodynamic four-wheeled vehicle ever. That superlative goes to something that looks like salmon fillet on wheels. The EQXX is, however, more aerodynamic than a regulation football (0.19). And its production sibling, the EQS sedan, is currently the most aerodynamic production car in the world. This is important to know because the EQXX's design was always shaped by its mission, not vanity.
"Efficiency is slippery, hence the 195-inch-long body that begins with a low and wide face and culminates with a luxurious longtail. Active shutters throughout the car optimize airflow depending on driving conditions, while a special algorithm retracts and detracts a massive rear diffuser as needed. Hidden door handles and aero wheels maximize airflow through doors and wheel wells, while an underbody tray seals the chassis to prevent turbulence. At speed, this equates to a feeling of gliding rather than driving."
— Jerry Perez, The Drive
"A tug of the EQXX's motorized door handle reveals the no-holds-barred interior of a show car, though a surprisingly comfortable and functional one. From the driver's seat, the spaciousness of the cabin is at odds with how little of the car's front end you can see through the windshield. While there are a few 3-D-printed pieces that we're told to be gentle with, the steering wheel and basic controls are familiar Mercedes stuff, making it easy to get situated in what is a near-priceless one-off. Ignore the judicious use of brightwork and ambient lighting, and the smattering of environmentally friendly materials — trim panels derived from cacti, mushroom-based seat inserts, and bamboo-fiber shag-carpet floor mats — are both attractive and a harbinger of what could filter down to future production models.
"Set off and the EQXX's feathery (for an EV) claimed curb weight of 3,900 pounds is immediately apparent. Although the rear-mounted radial-flux motor produces a mere 241 horsepower, thrust is plentiful, and the light, almost delicate steering is impressively tactile even at pedestrian speeds. With little powertrain hum or air turbulence to ruffle the ambiance, the main distraction is tire noise brought on by the car's modest amount of sound deadening. The overall vibes are responsiveness and good integration, despite the EQXX — with its quoted 7.0-second 60-mph time and electronically limited 87-mph top speed — being in no way tuned for spirited driving."
— Mike Sutton, Car and Driver
"Although technically a concept car, it feels entirely drivable and doesn't have the brittle show-car feel I've noted from concepts in the past. I pulled the door strap made of Biosteel fiber, and the door made of glass-fiber-reinforced plastic and polyamide foam closed with a reassuring thunk. Then I adjusted the seat, upholstered in a mushroom-based vegan leather alternative, and got quite comfortable in the EQXX — noteworthy as I'm a long-legged six-foot-six.
"Driving the EQXX didn't require learning a new interface; the switchgear and shifter stalk are in about the same places as in the EQB, while the haptic controls in the steering-wheel hub are merely a simplified new generation of the current layout.
"The most radical change was the super-long one-piece 47.5-inch display standing atop the entire low-set dash. Closer to the field of focus, with a more natural contrast level, I found it far easier on the eyes than the EQS's Hyperscreen.
"We set out and heard the whine of the motor and whirr of the drive systems. Mercedes hasn't put a lot of effort into NVH yet in this one-off — for obvious reasons — but it's actually quite good. The body feels rigid, and the steering remarkably normal and communicative. The EQXX's lower body is made of special low-CO2 recycled steel, and the entire rear portion of the EQXX is the largest aluminum structural casting done yet by Mercedes-Benz — with the damper domes cast in — but this futuristic pedigree doesn't give itself away.
"One clue as to the car's advanced design was the almost complete lack of wind noise. The EQXX cuts through the air with a remarkable 0.17 Cd. Its slim, specially developed Bridgestone Turanza Eco tires on 20-inch forged magnesium wheels don't generate all that much road noise, either.
"Little much else whirred underneath, either. The cabin is kept cool with a modern climate system driven partly from a 12-volt system that's fed mostly by a rooftop solar panel. A "cooling on demand" approach down below funnels air past the air-cooled battery pack only when necessary, while a liquid-cooling system manages only the power electronics and motor. Mercedes says it can keep pack temperatures not much above ambient temperature, but it hasn't detailed the cells inside the nearly 100-kwh pack quite yet."
— Bengt Halvorson, Motor Authority
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