What you're asking is basically a physics question. You might want to look into using Netwon or ODE. It's certainly not a DelphiX issue. You'll be using DelphiX as the basic sprite engine but the car handling would be handled by the physics engine.
If I was writing a serious racing game, I'd use Newton or ODE.
If it was just a simple game then I'd fudge some calculations together.
You might want to look at one of these books
Link
I own a copy of Physics For Game Developers by O'Reilly
That has some stuff on Car handling I think... it's been a while since I read it.
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