I understand this is a lot of work, but I think you overdid it big time. It's ok to make a jet powered like car, but it should be much more progressive. It's almost impossible to drive. Also I'd like to see a car design that distinguishes it significantly from other cars. Maybe you should take a look at the Red Bull X2010/2011 by Gran Turismo. I like your idea, but exaggeration = simulation failure. For me, this car doesn't belong in AC...yet.
A suggestion that I can give you is to try to keep a constant speed so that you can calculate when to steer better, and maybe to decrease turbo pressure using the numbers in keyboard's numbers row.
Thanks for the feedback, have fun :)