As far as the CV and Marauder comparisant, sure they're both the same basic design (the "Panther" platform) just as the Mustang and Cobra are the same basic design, but it's been my understanding that in addition to having different cylinder heads (32v) and different pistons (Hyperuetectic), the Marauder also has different suspension than the CV does. Ofcourse then there's also the 18" wheels that the CV doesn't have. So to say the CV is the same as the Marauder, is like saying that the Mustang is the same as the pre 2003 Cobra, and is like the 1964-70 GTO was the same as the 64-70 LeMans was.
And as far as the 4door vs. 2 door thing, I think that the big 2 door cars of old looked waaaaay better than the modern day 4 door cars do, but most of the body styles we have now wouldn't even look right with 2 doors anyway. Things are just very different now than they used to be in the way of cars.