It's a bit of a dramatization, but it's very true, and I think it's actually pretty decent. The full racing gear is pretty funny. I can't imagine what my wife would say if she walked in and I had a race suit and helmet on.
Coming from somebody who drinks regularly and plays GT sometimes while doing so, it absolutely affects lap times, crashing, restarting, and all of the above, even before being legally drunk.
I recall a seasonal from GT5 on the ring earlier this year (which I'm pretty good at). I was well over the legal driving limit and spun out at least a dozen times (and restarted each one). I was frustrated, but then laughed and said I'll gold it in the morning. Woke up the next day, sat down, and got gold on my first try, no spins, perfect lap. Night and day difference.
Driving while drunk in GT can be amusing, but driving while drunk on the road is not. That's what the guy did that hit and killed my younger brother and his best friend when they were just 16 years old. When they put "you can restart life" on the screen, it hit home for me.