I really thought someone else would take a shot at these last two.
Herb Thomas - 1951 and 1953
In addition as best I can determine Herb holds teh all time best winning percentage of any NASCAR driver with a significant number of starts. Like over 100 starts.
Herb won 48 of the 230 races he started a percentage of 20.86. Ain't nobody else really even close that I know of.