On the option of having a completely transferable set of wheels, I agree, but with certain conditions. I too missed the old system we were used to since wheels were transferrable (debutted in GT2). An option I'd have is, instead of trading them in for new ones, I'd want to be able to actually CHOOSE if I want to keep the old wheels or trade them in for new ones. I'm okay with the manufacturer-specific wheels. You may call them whatever you want- wheels, rims, ice, but I'm okay with the old style, so I wouldn't change that.
Now the second idea. In Gran Turismo 1, if you bought two of the same car, EVERY LAST MODIFICATION except the Racing Modification were easily transferred to the other car. I did hate the idea that left but, I think there would be good reason to this. Why would you want two identical cars set up the exact same way? I'm not saying it's a bad idea to get two of the same car, but you don't need to have two of the same car with the same setup. You mentioned the Lancer Evo VIII, so this is what you can do instead of have two cars set up the same way. You can have two Lancers. Based on your call, you can set one up to be your track racing all-star. Then, you can make the other car as a rally-exclusive car. A street car for rally. Call me Dr. John, and let me offer you my remedy for this problem. If you're preparing a car for track racing (circuit, drifting, etc), have one car, then prepare another for rally/off-road. You can also have two cars for this situation: you can buy parts for a similar variant of your car, and test out certain non-permanent enhancements (permanent includes Weight Reduction, Port Polish, etc.) to it.
To "Classic Anycar" now. That Auto Save wasn't very fun, was it? I'd toggle what should actually be Auto Saved. When I get into a car, I don't really think anything needs to be saved. I'd actually want to have manually loading games make a comeback. I'd hate having to go on a three-race losing streak and have it reflected in my results. I'd surely want to know what situations I can toggle for Autosave. These include buying parts for a car, getting into a car, finishing/retiring from a race, leaving from the pits of a race, and all that.