Drivers don’t get the full amount for a win. IIRC it’s in the neighborhood of 40%. That would mean the total for the win was about a million. That’s assuming the article actually got the number that Newman gets right and the 423K isn’t the total for the win.
Here’s the payouts:
the $423k is the total
http://www.jayski.com/stats/2013/pdfs/20indy2013results.pdf