Mate you really should go a modern-ish common car, and your best getting a holden or ford. I totally understand you wanting something out of the ordinary, and you should get that in due time but not as your first car.
When i was 18 i got a perfect condition magna through the family, which cost me 3 grand in maintenance in just one year, and then died i sold it for $100 to wreckers. Then i got a vt commodore wagon at 19 with 440,000kms and has been almost perfect the whole time.
It is still my main car and now has 494,000kms and is running as strong as ever even though i thrash it every single day at every corner and race off at every traffic light.
I wont be bothered getting another car until the engine dies but the engine has been bullet proof. And bullet proof is exactly what you want in a first car, then down the track if you happen to have extra money, go and buy an alpha or whatever as a second car.
I have a second car which is a perfect 1966 HR holden. But it truly is just a weekend car.
My girlfriend has a wonderful 1988 red e30 bmw, she bought it when she was 16, and we both love it, but the servicing and parts costs were astronomical, she grew sick of the bottomless pit of money and is now looking for a holden adventra because she is jealous of the low severing costs and reliability of my car.
By the time you're 18 you will have more money. and will earn a lot more when that time comes, so if you are working for a couple of years on a decent wage you will be able to get a car you really want. My next car will probably a renault clio sport or a v8 holden because i can now afford it
hope that helps