• A Mercedes-Benz CLA EV prototype toppled a record set by the Porsche Taycan
• Mercedes drove a CLA EV 2,309 miles in 24 hours around the Nardo test track
• The Mercedes CLA EV could become the most efficient EV on sale in the U.S.

Records are meant to be broken, and Mercedes-Benz has just busted one set by Porsche.

In April, Mercedes-Benz quietly took an electric CLA-Class prototype to the Nardo test track with the aim of seeing how many miles could be driven in 24 hours. The answer ended up being 2,309 miles, which set a new record.

Under what was internally codenamed Project N—the N stood for Nardo—the team took two close-to-production prototype electric CLAs and aimed to set a record. Porsche set the previous record of 2,128 miles back in 2019 with a Taycan.

The entire feat took 40 charging breaks, with each break lasting about 10 minutes. The 2026 CLA can add 186 miles of range, or about 36 kwh to its 85-kwh battery pack, in 10 minutes, according to Mercedes, when started at a 10% state of charge. The automaker said that 10 minutes should bring the pack to 50%.

That rapid charging is enabled partly by the CLA’s 800-volt electrical architecture, just like the Taycan has. 

The record-setting electric CLA started out at 100% state-of-charge and the team optimized the charging strategy in real time to take into account air temp and environmental factors such as wind. The team also had to take into account the fact the charger was located in a particular spot on the track, so the stops were planned, and the state of charge at which the car got plugged in was not consistent.

Mercedes said the ambient air temperature ranged from 55.4 degrees Fahrenheit at night to 84.2 degrees during the day.

The car’s average speed during the test was 96.2 mph with the car’s top speed of 130 mph reached during the session.

The team consisted of six drivers and three shift changes with the rear-wheel-drive CLA EV. A single 200-kw permanently synchronous motor sent 268 hp to the rear wheels. Its 2-speed automatic transmission aided with the efficiency, according to Mercedes.

The Porsche Taycan isn’t the most efficient EV on the market. That distinction is held by the Lucid Air with its 5.0 mi/kwh rating. But the Taycan consistently overachieves and overdelivers above and beyond its EPA range ratings in real-world driving, which could be attributed in part to its 2-speed transmission. Perhaps Porsche was onto something with having a taller second-drive ratio. Mercedes mentioned a 5.2 mi/kwh efficiency number for the CLA EV, though nothing’s been made official yet. Should the team at Mercedes achieve that type of efficiency, it could be because of the 2-speed transmission, and herald a new efficiency king when the 2026 CLA EV arrives later in 2025. 

Mercedes-Benz paid for travel and lodging along with some German pretzels for Green Car Reports to bring you this firsthand report.