One thing that is bothering me about this shell is the roof line. See the floating tiles in this pic:
https://cianesimshome.files.wordpress.com/2020/01/screenshot-27-2-e1578588232684.jpg
When I was playing with @soocoolsim Elf Express cars, I redid the roof when I expanded the car this way:
https://cianesimshome.files.wordpress.com/2020/01/screenshot-30-1-e1578588267240.jpg
It has those little horns on the ends, but no floating tiles.
Is there some way to make the floating tiles disappear without redoing the roof? Probably not, but I thought I'd get your take on this before attempting a fix.
I'll be out for several hours now. I hope you are all having fun with your designs.