I think an interesting automotive addition would be windshield sunshades - the ones that cover the windshield and block out sun on bright days..
They could work well with humorous, beachy. and retro designs, as well as other styles. They are currently for sale on some retail and POD sites.
@Sea-Change Oh, I second that!! We currently have a heatwave and I can see them selling really well - especially during summer!! 
I requested this… ages ago 
Glad to see someone else refreshing the request
Thanks for the feedback in this thread!
Hi @ Sea-Change
Many thanks for this suggestion. I will be sure to pass this along to the Team for consideration.
Lisa 🌺
I subject that last year, but It never went through perhaps Zazzle might read you now.