Fiberglass Roof?

[Phoenyx]

Plus, the 'french car' would have been designed for it in the first place. G-bodys weren't.

 

[85 Cutlass Brougham]

The DS was actually quite a good car after the initial bugs were worked out with they hydropneumatic suspension (yes, it had factory hydraulics! They controlled everything from the brakes to the suspension to the transmission and even the throttle, if memory serves.)