I've had several of the German made Opels over the years, including the GT. Yes they were heavy and underpowered, not high performance cars. However they were also indestructible, ridiculously reliable, and lasted forever without much fuss. Furthermore they were very comfortable, great driving for trips or cruising, easy and inexpensive to maintain, and all around excellent quality in every aspect. As much as I like the X, if you're honest you really cannot say any of these things about it. One thing I hated about the GT was the tendency for Americans to refer to it as a baby vette....I hate American cars and that just ruined it for me.
The later (1975) German Opels were fuel injected with a Bosch system very much like on the US X's. However the FI ones sold in the US also came with the larger "impact regulation" bumpers, much like the later X's. Unfortunately the GT was discontinued the year before the FI was offered, so I do not believe it ever had FI (at least as far as I know in the US). But that also meant the GT never saw the big 'impact' bumpers, which would have killed the body style.
But in regard to this thread, I'm not sure the Opel GT is a "wedge"?