Round about the 1920’s you could have your own fold up electric three wheeler and leave it in the hallway.  

Mary Tripsas, Harvard prof, may have a point that it was too early for the market then but what about now?  It’s all a question of it fitting into a familiar category she argues.  We have tended to think that it’s a question of fitting into a consumer’s lifestyle – if you don’t have a big hallway you don’t think of this car.