Audi has promised a range of around 300 miles for at least one variant in the 2024 Q8 E-Tron lineup—and it has now confirmed that number for Sportback versions of the crossover EV. The EPA has published official range ratings for the Q8 E-Tron, which replaces the former Audi E-Tron SUV and E-Tron Sportback. The Q8 E-Tron Sportback, a…