Here's what looks to be an excellent webpage about one of the Sunswift Cruiser Class solar racecars. It's claimed that the Sunswift 7 has a 0.095 Cd. Compare that to one of the Bochum University cars (that's linked in the webpage) which is said to have a 0.135 Cd. The Sunswift has a much better Cd without having the teardop-shaped cab forward form, but it has an underbody duct from front to rear, whereas the Bochum's only have a rear duct. So, a through-duct seems to be a good way to get a very low Cd, but that adds challenges to setting up the drivetrain, passenger compartment, etc. I'm guessing that a combination of the Bochum (teardrop-shaped cab forward) and Sunswift (through-duct) might be better. In other words, mimic the Sunswift but make it cab forward. I'm hoping to try designing and building something similar to this for a fairly low-speed get to work and grocery getter, one of these years.
https://www.linkedin.com/pulse/sunsw...ng-graham-doig