Some of the skill transfers over. Video games sharpen your reaction time and visual acuity, which would definitely help in a real life driving scenario. Now obviously, if you play arcade racers all day you won't have a clue what you're doing in a real car. If you play something like GTR2 all day? You'll most likely do much better than you would with no prior "training" stepping into a race car because you'll know what to expect for the most part. Now obviously learning your machine IRL is a very important aspect of being good at racing as well, so I doubt the validity of this story. I don't think anyone can just get in a race car and own it up, video games or not. You'd need at least a day of practice...
I don't know GT5 with a G27 does a real good job of feeling authentic just wish I could simulate the g-force.