Even if there was a 100% realistic sim, as in complete and accurate modelling of all car components, physics and track properties, you'd still be sitting in front of a 2D monitor in your comfy chair, using a (relatively speaking) cheap hunk of plastic that calls itself force feedback wheel. So the answer is: no.
Of course you can always ramp up your surroundings to be closer to reality, build an actually good wheel + pedals (technically probably the easiest part to get right if you're dedicated), add 360° projectors around your car frame combined with some magic trickery to make it look 3D, etc. etc.
But even if you go to such great lengths, it wouldn't be like the real thing. A really important factor in real racing are the forces acting on you, and there simply is no technical solution for that. Current "personal" motion simulators are, to put it bluntly, a joke. And at that point it's already much cheaper to just go race in a real car.
From a technique standpoint, a simulator may give you a slight advantage, because you can freely find out what a car will do in what situation without actually risking your life. Assuming a completely accurate simulation, you can test out what will work and what won't, see which lines work better and what driving style is required to preserve your car, all without actually spending more than what's on your electrical bill. Not to forget the racecraft aspect (how to behave around other cars), which is probably one of the bigger things you can learn from a sim.
But you have to keep in mind that all that knowledge is highly theoretical and the missing forces are a huge disadvantage in regard to driving fast. Sure you can learn to feel/predict the sim and drive insanely fast in it, but that's a completely different way of driving than the real thing, where you can actually physically feel the car with your whole body and become one with it. Having to rely on visual and audio cues only makes it a lot more difficult to sense certain things in the sim, like for example when the car starts to oversteer - any mechanical cues from the FF wheel come far later than you'd feel in a real car. The second you drive in a real car you also throw out your way you drive in the sim completely, simply because the input is vastly different.
tl;dr: sims can give you a slight advantage in some aspects, but it will never replace actual driving experience.