@Aramike
I once had the opinion that I could handle a car just as well when I was pretty tired as I could when being wide awake. Then I started to drive Rallies at my Computer. I know now that I don't even have to start the game when I'm tired because I will eventually find myself "parking" at a tree. That opened my eyes for that I might handle a car normally under good conditions without incidents but I wasn't so sure any more whether I could react on time if anything unlikely happened (deers crossing the street, the guy in front of you steps hard on the brakes for some reason, aquaplaning....).
If you have a racing simulation (a proper one not something where you have to drive in an oval) then try it out yourself. Drive around while you are sober and see how good you manage and then drink your six pack and see if you are still driving the same.
I know that this is just simulated stuff but it allows you to compare your skills while being sober, tired, drunk or whatever without endangering yourself and others.
The results are sometimes shocking.
