I don't know who, or where I learned this (definitely not my parents, they tried to teach me to turn over every penny 3 or 4 times before I spend it), but money comes and goes, time does not, so spend the money you don't need to keep a roof over your head, and food in your belly. not great financial advice, but life ends up being a bit more fun doing things than looking at portfolios.
does it make financial sense to buy 3 cars in a year? probably not, but if you trade the car in, at least you don't take the tax hit (well, I guess that might depend on the state). if you aren't satisfied driving the car then don't keep it. is a Mustang GT going to satisfy though?
that power to weight ratio in the ZL1 is going to be hard to beat, and the Mustang is better than the GR Corolla for sure, but not by a lot, and not in the same area code as the ZL1.
if it's the looks that kill, then yeah, the GR Corolla is always going to be a pug compared against a german shepherd, or a blue heeler, even if you toss a wing on it.
just go out and get a C5 Corvette for cheap, toss a turbo kit at it, and hope you don't break the trans, although with the money you'll save with this option you can probably buy a few backups to keep at your prefered shop.