For AI driving I am using spline. You need to make AI to follow dynamic location that is following that spline. Push the follow location 1000-1500 (depending speed) forward when car comes close enough. Make AI have input towards the follow location, the smaller angle there is (between car world yaw rotation and look at yaw between car and spline location) to turn the less input. And to make AI make 180 turn, you can check when the absolute angle is bigger than 45 degrees then just make the input values to be inverted so the car moves back and turn opposite direction. Over that I have stuck checks and obstacle avoiding checks. Result is quite chaotic but getting better slowly.
When spline end you can check nearby spline starts or even store variable in to spline actor with variable than have the next spline(s) to choose.
For racing game probably you just add rigth vector offset so you can make cars pass each other even they all follow the same spline path.
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