[dunnere]

The youngest winner of the Daytona 500 is Trevor Bayne, in 2001, at age 20 and a day, but the Phenom that was Joey Logano won in his 2009 ROY season, at 19 and some change, a full year + younger than Kyle Busch, who was 20 and a couple of months when he won in 2005 (thanks to some good ROY questions here, that is stuff I've been reading about).

Nationwide is not something I know, but seeing as how Logano moved up pretty quick, I'll say he is the youngest to win there, too, at age 18.

Truck Series? No clue, but I'll guess Kyle Busch at age 19...I don't follow any Truck Series stuff...

I do not know any of the tracks without looking it up.

Tony Stewart won his first race his ROY season, at 28, at Richmond, following it up with wins at Phoenix and Homestead. LOL