I’ve made a new convertible based on the Lexus IS. I think you need to have a convertible when you are a ‘premium’ brand. The front and taillights are a little bit different and the front window is also smaller. And of course it’s an 2 door instead of an 4 door car.
A hybrid version of this convertible would be an unique offer, but it will shrink the trunk space even more. So it’s not very likely to happen