[Number 3]

Originally Posted by Dragoneye

So, 3......If this is all standard knowledge...why is it that some cars (coughmustangcough) pale in comparison to others? Is it cost? Lack of expertise? Intentional Compromises to achieve other goals?

It is cost, engineering compromises for styling and or features. Simply put if you want to have a vert, it's less rigid. You can't cut the top off the box and get the same result.

Or you can do like the Corvette and start with a structure so good that when you put a targa or vert on it, it simply is indistinguishable. I think the vette is less than a 1 Hz difference coupe to convertible.

Look at the underbody of the Camaro convertible. Those braces are a big part of the weight. But if you didn't allow for space for those braces in the original design, you are "stuck".

Not so much a lack of expertise. You just have to make compromises for cost, mass, investment and packaging space. If you have the $$$ then you can add unobtanium braces which are miraculously infinitely stiff. But if you din't allow the space for the bracing or the optimal points on the body to attach them you get a less than optimal solution.

But from experience, you are better off planning for a convertible from the begining than to try to do it after the fact.

As I recall, we started the Corvette C6 from the XLR which was a convertible. Made doing the coupe way easy.