The Hyundai Ioniq is a similarly shaped EV as the Model 3, and it gets very similar numbers - 133 MPGe (Ioniq) versus 141 MPGe for the best version of the Model 3 Standard Range
The Ioniq has substantially less range than the Model 3, and is a much smaller car. If the Model 3 still gets slightly better MPGe despite those differences, I'd say Tesla still has a pretty significant efficiency advantage in this comparison.
According to the specs on interior dimensions listed on fueleconomy.gov, the Ioniq is actually bigger - 96 cu ft passenger and 23 cu ft luggage volume, vs. 97 cu ft passenger and 15 cu ft luggage for the Model 3.
So they've sacrifised range by installing less batteries, gaining more luggage space, lower weight and lower price.
The Ioniq has substantially less range than the Model 3, and is a much smaller car. If the Model 3 still gets slightly better MPGe despite those differences, I'd say Tesla still has a pretty significant efficiency advantage in this comparison.