Part of it could be due to the motors, but I'd bet quite a bit of the inefficiency comes from the poor aerodynamics of the boxy design.
Something that I haven't heard about for any EVs yet, is the upgradability of batteries as the tech gets better (and cheaper). 10 years down the road, will I...
This video shows the R1S rear storage, and Brian Gase (Chief Engineer) says there's an "inflatable spare tire". Not sure exactly what that means, but it doesn't sound like a full sized wheel...
Jump to 13:15 ^