Hi Utajoker - I doubt any of us have completed the game, you just need to have unlocked the ability to buy the car, and have enough cash to afford it. Give it a go, it's loads of fun and really addictive.
If you splash all your cash don't worry, you can sell that car next week and there's no depreciation so you get your cash back, also each time trial you do you get cash for anyway, so money worries quickly disappear.
If you splash all your cash don't worry, you can sell that car next week and there's no depreciation so you get your cash back, also each time trial you do you get cash for anyway, so money worries quickly disappear.