Aptera's First Solar Road Trip. 300 Miles, One Charge

What's new here? College kids have been doing this since the 90s: https://en.wikipedia.org/wiki/World_Solar_Challenge

Some look close to like a real car, that one EV + solar, 25miles/KWh https://en.wikipedia.org/wiki/UNSW_Sunswift#/media/File:Suns...

I'd venture a guess - Aptera went for 3 wheeler because certification as a motorcycle is much easier than as a 4-wheel car. Unfortunately 3 wheels - 3 vertical columns resisting the upcoming air - may be less aerodynamic than 4 wheels which are only 2 vertical columns resisting the upcoming air. Add to that that for the same stability you generally need the paired wheels in a 3 wheeler wider than the paired wheels in a 4 wheeler - that again worsens the 3-wheeler aerodynamics.

There's two different classes in the WSC - one is basically 'make a race car' with very little view to practicality, most of the rules are about limiting the competitive speed to be below the speed limit and having some semblance of safety. Entries to this one are almost always 3 wheeled because it's optimal from an efficiency point of view (aerodynamics and rolling resistance). (Two-wheeled designs are not allowed). The other class (which the car you linked entered under) is meant to be a bit closer to a practical vehicle, and one of the rules is that it needs to have four wheels. It also is allowed a larger battery, which can be charged at certain points during the race (the other class starts with a fully charged battery but it's nowhere near enough for the race, and only solar power is allowed from that point on).

Having worked on one of the cars for this, I don't think solar panels on cars actually makes much sense for useful cars. If you can put them on cheaply enough, then they are maybe a nice free boost in some circumstances, but the compromises in the design needed to get the efficiencies necessary for solar panels on the car to power the car are quite extreme.

Optimal aerodynamic efficiency on a 4 wheel car still requires a narrower rear, with a corresponding shorter rear axle to make the rear wheels roll in the slipstream of the front wheels. This can be seen on two of the most aerodynamic cars of all time, the GM EV1 and Mercedes EQXX.

>make the rear wheels roll in the slipstream of the front wheels.

thanks. That is in general what i meant by saying "4 wheels which are only 2 vertical columns resisting the upcoming air", i missed the shorter axle as being the most aerodynamic, and your description is just much better and more right detail level correct.