First, let me say that I get that whole "want something different" vibe as I swap cars on average every 13 months. Yes, I have a spreadsheet.
Second, I have a CT5, not CT4, so my perspective is a little different. And I had a S550 GT, not a S650DH, so that's a slightly different animal. And the Mustang was my occasional/track car, not my DD. I bought it new.
So, let's hit the positives of the 'stang. Just a really nice V8 engine, great sounds, very linear with a good balance of torque and horsepower. The transmission is also well done, good ratio spread, heavy but easy to modulate clutch, heavy but not as notchy as GM transmission/shifter. I really had no complaints about the drivetrain.
As a track car, it's quite lacking. Sounds like that's not your concern, so we'll skip all that. However, largely because it's a Ford and extremely popular, aftermarket parts are plentiful and cheap. I upgraded my brakes and some other stuff (who can remember?) mostly by buying used from guys off of forums like this. When I decided to part with the car, I sold every bit of that stuff for close to what I had paid. For example, I bought a set of take-off "Bullitt" wheels with new Michelin PS4S tires for $1400 IIRC. I sold them, used with a couple of hard track weekends on them, for the same price. Maybe more.
The car also looks good, paint, fit & finish was good and the only issue I had with mine was a check engine light that came on during a track event and went away on its own. I never bothered to investigate the cause. The seats are acceptable comfortable.
The real let down was the interior. It is just Hertz-level quality plastic. Just cheap, thin, horrible plastic everywhere. Even on a premium model with leather, it's the same plastic everywhere. I can hear you now, but Michael, they do that to save weight. Ha! Ha, I say. It's still a pig. It weighs around 4000 lbs, the same as my yuge Cadillac. It's a big car the 'stang, it feels big, it looks big. There is little to no steering feedback, the brakes perform well but again don't really communicate all that well, and the handling is... well, it depends if you get a base car, or one with the performance package or the handling package. Those tighten things up a bit, but they also degrade the ride quality quite a bit. You may not care, but I did.
It's a Ford, it's built to a price point, and I think the base car with no options, before the pandemic when you could get them quite cheap after discounts and such if you didn't option it up, those were a good value. Now with the higher prices, fewer discounts and did I mention the higher price, eh, not so much of a value. Since I don't need a back seat, I replaced the Mustang duties with a Corvette, which is a better car in every respect (except perhaps the shifter) and much more capable out of the box.
