The recently announced EPA range rating for the upcoming 2020 Tesla Model Y Performance (Long Range and All-Wheel Drive) version of 315 miles (506.8 km) surprised many of us, as it's actually about 16 miles (25.7 km) or 5% better than the corresponding 2020 Tesla Model 3 Performance (LR, AWD) - see the range/efficiency report for the Model 3 here.

There might be some questions about wheel sizes, but in general we would rather expect the opposite (assuming the same battery capacity), as the Model Y is a noticeably bigger car than the Model 3.

Two things might explain the outcome:

the Model Y is more efficient than the Model 3
the Model 3 is now also more efficient, but hasn't yet received an updated range rating