I take a fully charged 2020 BMW i3s with range extender out on the New Jersey Turnpike for a 70mph (113 km/hr) highway range test.

Test notes:

Tires were set before the drive to BMW's recommended pressure.
Temperature: 89 F (32 C) degrees at the start and 93 degrees F (34 C) at the end. I had the air conditioning on and set to 70 degrees the entire drive.
Wind: There was a mild, 3 mph crosswind from the west.
Comfort driving mode was used.


Results:
126 miles (203 km). The EPA range rating is 126 miles.
Efficiency: 3.5 mi/kWh - 17.7 kWh/100 km