We know car prices are pretty arbitrary. The price difference between building an ATS or CTS versus something similar with a Chevrolet nameplate is going to be slim to nonexistent. An ATS that would go for 20 grand more than a Camaro (or more accurately, a CTS that would go for 30 grand more) might cost GM an extra grand to make over, say, a Camaro on the same platform even with additional equipment.
I've driven my sister's Camaro when I go to Phoenix and I've rented a couple of Challengers and Mustangs on my trips, so I thing I can say what I'd like by saying what I like and dislike about these 3 rides.
I love the Challenger's room and (save the soon to be replaced dashboard) general interior comfort. I feel Mustang easily had the best interior, but I would never buy one because of the extremely intrusive headrests. I have a neck issue which if my head's pushed forward for long periods of time, I develop a headache and neck pain that lasts for days. In the 80s, the large headrests in Fords (including Mustangs) could pivot and were comfortable. Current Camaro interiors I think seem cheap, even with the revisions made last year.....but I like the seat design.
6th gen Camaro interior: Although there's no way it'll have Challenger-like room, I'd hope it isn't as claustrophobic inside. I'd like to see the seats be as comfortable and supportive as the SRT seats in the Challenger. But don't lose the headrest design....or the sport look of the current seats. One thing that would be inexcusable is another cheap interior. The doors and dash looked great on the concept, but hard smooth plastic covering most of the door and the empty space on the passenger side of the dash was a bad idea and IMHO ruined the interior. It made it look and feel cheap.
The thing that takes a lot of getting used to in the Challenger is that it's high hood makes it feel big. Visibility is actually good, but you're aware this isn't a sports car. Camaro feels more like driving a tank. Camaro is actually a smallish car with a huge number of optical illusions that make it feel big. It's no bigger than a Mustang, but because of it's high beltline, mammoth sized wheel size, squashed roof, and gunslit sized windows, the Camaro looks and drives like it's as big as the Challenger, but without the visibility. While you sit on top of a Challenger, you feel like you're driving Camaro from the floor. Mustang seems to get it right with optical illusions of it's own. A low beltline makes this same-size-as-Camaro vehicle feel and look smaller. Rear overhang on the current Mustang is identical to the 2004 model, but because Ford designers clipped the rear sides, the bulky rear end "looks" gone, and the entire car "looks" smaller.
6th gen body: More visibility. Less effort making it look huge, and more effort making it look, feel, and drive sporty.
The biggest thrill of my Fox-Mustangs wasn't that they had a gazillion horsepower. It's that they felt like they did. Stop the pedal of a 5.0 Fox era Mustang, and the chassis shook, the nose inched upward as it squatted on it's rear 4 shocks, and with the thin soundproofing, large windows, and paper thin floorpan felt like you were taking off horizontally in a Saturn V rocket. Nevermind that it had only 225hp and only about 300 lbs/ft of torque. You FELT like you were being launched.
Nowadays, everything is far too smooth and anti climatic....Every base V6 version of every pony car in showrooms today can outrun that Mustang to 60 and even the quarter mile. The V6 Camaro will simply flay it in top speed (135-140 vs 155). But even the V8 versions of these cars feel dull by comparison when you mash the pedal. Sure, the scenery accelerates past you till it becomes a blur, but to paraphrase an old song, "The thrill is gone".... My 97 Z28 was a more exciting blast than the current SS.
6th gen Camaro: Even though today's regular buyers have pushed Noise Vibration Harshness (NVH) standards to the point where riding in cars is akin to sitting in stationary living rooms, how about a performance version with less sound deadening, and more NVH? Include it with a performance pack that also includes V6s and bring the thrill back.
Finally, It seems obvious that Challenger is the most successful of the pony car designs. It looks classic and hasn't aged at all, it's sales have increased steadily since it was brought out, meanwhile, Mustangs look a bit boring and Camaro needed a redesign to keep looking fresh even though it came out 6-8 months after the Challenger. While having a design that keeps looking good that long is about as rare as genuine bigfoot sightings, and I in no way advocate keeping body designs unchanged for 6+ years, it shows that clean designs work the best. I'd like the next Camaro to skimp on the styling clichés. Focus on great basic styling and clean sharp looks. You can always get expressive with grilles and taillights which can be changed as updates. But a good clean body is what makes a classic.
These next round of pony cars are likely to be the last ones with the original formula.
Gen Xers who were raised on turbo 4s and X-boxes, reach 30-40 years old and start taking over as key buyers in this market segment. CAFE won't kill these cars, but V8 engines will become the GT500s, ZL1s, and Hellcats while V6s will take the place V8s have today. Unless the cars are killed outright, the new Mustang and the upcoming Camaro will still be around for 2020 with no more than cosmetic changes and about to be replaced with whatever is next. By that time, today's key buyers of Camaro SS, Mustang GTs (45-55yo) probably would have moved on to another market.