Excellent points!
I'm no racer at all, but the "downgrade" from 3.8 to 3.0 displacement, with an "upgrade" to turbo seems like a HUGE advantage as long as you can stay on boost, but nothing is keeping the other cars in the same class from having the same platform (and I suppose some may). I seems to my eye that this guy obviously knows how to use his car to its best advantage.
I suspect that the RSR suspension platform also comes dramatically into play here, allowing for his fantastic maneuverability and maintaining his momentum through traffic.
I'm not sure why he didn't get a better position during time trials (maybe he had mechanical issues?) but he does seem to have a big stick to swing there, and swings it with confidence.
The main reason I posted it, is that it set me back a bit the first time I watched it. Plus its fun to see an older platform eat new cars alive once in a while. Once in a while...
Hope you enjoyed!