Andretti, who was fired in June as driver of the No. 43 entry for Petty Enterprises, posted a lap of 182.708 miles per hour in a Chevrolet Monte Carlo.
"We had a good test here and that played a big part in it," said Andretti, who has driven in nine Indianapolis 500s and all nine Brickyard 400s. "The weather was pretty similar to the test, it was actually hotter."
Jimmie Johnson was second at 182.645 mph, followed by Joe Nemechek at 181.3398 mph. The top three drivers were in Chevrolets.
Dave Blaney had the fastest Ford Taurus and was fourth at 181.148 mph. Ricky Rudd rounded out the top five in another Ford at 181.505.