So, I think we need [ul]Antenna’s, Sun and Moon Roofs, Filler Caps, Trunk/Boot openers, the ability to put the name of the car on the car, Pop-Head lights, Drum brakes for older cars, a fan on the engine, exposed mufflers under the rear bumper, centrally alligned mono-exausts, various Convertable tops.[/ul]
Almost all of this has been previously discussed, please use the search function next time.
You forgot side-mounted exhausts 
That too has been discussed 
.
Use search function please. This is lot of art effort for little result! Cabrios can come, is easy to do, but developer will make only one with roof. They said that interior is to much work.
This would be great! 
I would really like to see pop-up headlamps for the '90’s people.