12000 gets you a lot of SERIOUSLY capable machinery. I’ve driven a couple of these in real life and all of them in video games. I’ve worked on most of them. They’re about the best drivers’ cars I can think of; tremendously fast and built before the intrusion of driver “aids” like traction control.
It gets you as good a C4 Corvette as you please (1984-96). That’s classified by the SCCA in A-stock and is the dominant car in the class. They do 13.5 second quarter miles, about 160 miles per hour, and get around 25 miles per gallon on the highway. City mileage is just barely the wrong side of 20. My time on Grand Valley East with this car is 1:13.4. I expect to see some rather rough early C5s around this sort of money soon but I’d prefer to have an older car in better condition.
It gets you a 3rd-generation RX7 but I don’t recommend those because the turbo rotary tends to go “bang” at random. I did 1:11.8 on Grand Valley East, making this probably the fastest stock car you can get for twelve thou.
It gets you two Nissan 300ZX Turbos. This is the sportscar everyone forgot about. 23 MPG city, 30 MPG highway. 14 seconds in the quarter, 155 MPH top speed, and 1:14.8 on GVE.
A late-90s Camaro/Firebird with the aluminum LS1 V8 is in that price bracket. Do not discount the “redneck rocket”. Beyond anything else, they beat a LOT of cars you don’t expect them to in the corners, and they beat almost anything on the straights. They run high 12s in the quarter. They get over 30 miles per gallon on the highway.
The Miata and MR2 are seriously good cars. They’re cheap to run and service. They’re terrific to drive. They’ve got excellent reputations for reliability that are entirely deserved. If you don’t really care about straight-line speed they’re the best options you’ve got. Best of all, they have great owners’ groups that’ll give you advice on any difficult mechanical work, and often organize great group drives. They run high 15s in the quarter and get 25-30 MPG.
On one hand, the “big iron” (usually “big aluminum” nowadays) has a lot of things going for it. They’re no more expensive to insure than the smaller stuff (a Honda CRX is the most expensive car to insure), they were made after the automakers knew how to make a car reliable and durable but before they got rid of steering feel, and the gas mileage is about what you’d get out of a Miata.
On the other hand, I’ve looked at your choices and they’re all great. The Celica is fast if you get the 180-horsepower engine (in the GT-S) and the six-speed manual box. The Mazda6 was described by EVO magazine as better than an E46 BMW 3-series to drive. They’re about the most reliable cars you can buy.
As for wheels and tires, don’t bother with anything bigger in diameter than the factory size. What matters for cornering speed is tire width, and you shouldn’t need to go overboard with that, either - the stock size is usually about optimum on most sporty cars nowadays. Plain steel wheels are often just as light as expensive alloys. The tires matter a lot more. Post a second thread if you want tire recommendations.
One suggestion: Spend $10000 on the car, and spend $1500 at the local Sears Roebuck buying a very large Craftsman hand tool set. This’ll contain most of what you need to work on your car. Get a set of jackstands and a decent (hydraulic) shop jack. Being able to work on your own car gets rid of a major expense. Don’t do tire or brake hydraulic work, and don’t be afraid to ask a local mechanic for advice when you get stuck. He’s gonna hit on you anyway so at least get useful information out of him.
