Safari Condo has a new fixed roof Alto trailer model: A-2124. The 'A' is for 'Aerodynamic'. It is very pointy on the front end extending all the way to the hitch. It's very angular overall; no rounded front and real like the F-1743 that ecarfan has. The new model's roof slopes down slightly in the front and rear. The roof's center section is flat and level. In the rear of the trailer they sliced off the corners at what appears to be a 45 degree angle, leaving a flat, upright section in the rear center. The wheels have flat 'aero covers'. All this results in some compromises in the inside seating/sleeping areas. There is a facebook video by the the manufacturer. They say they did virtual wind tunnel modeling and this trailer has 50 percent less drag than other Altos and will enable the tow vehicle to get 13 percent better fuel efficiency. The model A-2124 has not shown up on the Safari Condo website yet. It is reported that the first trailer was sold to the owner of a Tesla Model X.