INDIANAPOLIS (AP) _ Michael Andretti may be a little older, a few years removed from the cockpit and, as a result, forced prove he can still guide an Indy car around the Brickyard.

No reason to call him rusty, though.

Andretti easily topped 220 mph Sunday at the Indianapolis Motor Speedway, the fastest among a handful of drivers who went through mandatory testing including his son Marco, two-time Indy winner Al Unser Jr. and three first-year drivers.

``It was really a special day, for sure,'' said Michael Andretti, who last drove at Indianapolis in 2003. ``I'm very happy with the way I feel in the car, no rust or anything.''

Mandatory testing for this year's crop of rookies began Sunday; Unser and Michael Andretti were required to take part because they had not competed in more than a year.

``I don't care,'' laughed Unser, who decided to make a comeback because he was simply bored after one year of retirement. ``It's additional practice, which is great.''

Unser came out late in the day and took nine leisurely laps, with a top speed of 206.387 mph. Andretti was the fastest, completing 51 laps with a top speed of 220.999 mph, while 19-year-old son and rookie teammate Marco Andretti had 85 laps and was second in speed at 220.572.

Qualifying speeds last year topped out at just over 227 mph.

Michael Andretti, one of the most successful open-wheel racers in history, has never won at Indy as a driver. But as a co-owner of Andretti Green Racing, Michael won the 500 last year with driver Dan Wheldon.

Marco joined the team after Wheldon defected to Ganassi Racing, and Michael decided to make a comeback so he could drive in Marco's rookie race.

``The guys, as a joke, put three (rookie) stripes on the back of my car. But they're gray stripes,'' the 43-year-old Andretti said.

Full practice for the May 28 race begins Tuesday.

The other rookies on the track Sunday were P.J. Chesson, driving for the new Hemelgarn team co-owned by NBA star Carmelo Anthony; Arie Luyendyk Jr., son of the former two-time winner; and Townsend Bell, a veteran of 22 IndyCar and Champ Car races at other tracks.

Marco Andretti, who won the developmental Indy Pro Series race on the Speedway's road course during the U.S. Grand Prix last year, was the first to complete the four phases of the rookie test on Sunday, taking just an hour to finish the series of 10-lap runs at increasingly faster speeds.

``Growing up here and basically having this my second home, it's good to finally say I made it,'' he said. ``I'm definitely excited, but I can't think about all the pressure, because then it'll keep adding on me. I need to respect the place, but I need to go out there like another race track and try to go quick.''

All three Andrettis took part in a track-opening ceremony Sunday morning, driving two laps, side-by-side, around the 2 1/2-mile oval. Marco and Michael were in this year's Dallara race cars, while Mario drove the car he used as a rookie in 1965.

``I'm surprised it's really running,'' he said of the vintage Brawner-Hawk race car. ``It didn't stop. Actually, we could have kept right on going, so that's a good omen.''