We test an electric Mercedes that can go 747 miles on a single charge

Enlarge / There's only one Mercedes-Benz Vision EQXX, so bringing it back in one piece was important. (credit: Jonathan Gitlin)

IMMENDINGEN, GERMANY—Driving off in the Mercedes-Benz Vision EQXX was slightly more stressful than I had anticipated. Not that it's difficult to drive or hard to see out of the low-slung streamliner—it's just the only one in existence.

Mercedes wouldn't tell us the program's exact budget, simply warning us that the sole EQXX should be considered priceless, but I'd guess it's somewhere in the range of three Bugatti Pur Sports.

Like the Bugatti, the EQXX was built to an engineering brief—in this case, the aim was to build an electric vehicle capable of at least 621 miles (1,000km) on a single charge. Also like the Bugatti, it's road-legal: In April of this year, less than two years after the project was given the green light, the team drove the EV 625 miles (1,006 km) from Sindelfingen in Germany to Cassis, France, arriving with 15 percent state of charge in the battery.