Two people in Belgium have set a new “hypermiling” record for the Tesla Model S, after driving the car for 901.2 km (about 560 miles) on a single charge. In a blog post published Monday, Steven Peeters and Joeri Cools said they drove a Model S P100D around a closed loop in Belgium, adding that it took them 23 hours and 45 minutes to complete the feat.

Hypermiling involves driving a car at maximum fuel (or electrical) efficiency to see how long it can run on one charge or tank of gas. The hobby involves driving at slow, constant speeds without breaking or stopping, and, crucially, without running the air conditioning. Hypermiling is not the best indicator of a car’s range, as Electrek notes, but it can provide insight into how driving habits can affect it.

The previous hypermiling record for the Model S was set in 2015 by Casey Spencer, who drove a Model S 85D for 550.3 miles on a single charge. Spencer drove his car at about 22mph, whereas Peeters and Cools drove slightly faster, at 24mph. Their overall consumption was 88 Wh/km (54.7 Wh/mile), which is a record low.

They also carefully mapped out a route that would allow them to drive with minimal traffic and intersections, and on flat roads. Driving on a closed loop, they say, gave them an extra advantage.

“Although it might be more beneficial to keep driving straight and preferable with a tail wind, our approach had the advantage that we could learn from each round,” Peeters writes in the blog post. “By the time we finished the attempt, we knew perfectly how to take every turn and roundabout to make sure we drove with the least possible consumption.”

In a tweet on Tuesday, Tesla CEO Elon Musk said that “with the right tires,” the Model S P100D should be able to drive more than 1,000 kilometers (621.4 miles) on a single charge.