The moment I try to drive it the car instantly spins out of control, handles even worse than the default cars
Actually it has immensely good handling at high speed (due to high down-force allowing for quick cornering without flying off the road/track). I think it's more a case of you having a heavy foot. If you have a controller or wheel, try using it to slowly ease the power in as apposed to letting it all go at once.
No it didn't. Works absolutely fine here in prerace and experimentals. Now quit spamming, else this applies: http://www.beamng.com/threads/7384-General-discussion-chat?p=165565&viewfull=1#post165565