I believe a lot of the problem now is not the car makers and designers but rather the rules and regulation put in place by the government regarding side impact safety, crash testing certification and the like. I remember reading about one newer car, I think perhaps a Corvette with an options package, the designers had wanted to swap in some more supportive seats but couldn't because they would have had to crash test a bunch of cars to re-certify the car with the new seats and they didn't have the budget to do that.
I'm pretty sure it's side impact requirements that keep the belt-line soooo high on the Charger/300M, and then in turn the Challenger. The Challenger had to be built off that platform because it is so expensive to qualify and come up with a new platform for a low volume car like the Challenger. Why do you think it takes 3 years or so to get a facelift which is just headlights, taillights and bumpers on a new car? It's because of the required crash testing. It is certainly not because the designers and car companies have no desire to have a fresh look in the showroom every year like they did back in the 50s, 60s, and into the 70s.
The Crown Victoria is dead now too, it's a big 4 door but it's the last body on frame, rear drive, V8 car left. Gov't mandated stability control and new rollover standards mean it can't adapt so it's dead. Usher in the FWD unibody V6s...
