ESPN IndyCar

JOLIET, Ill. -- Even at 215 mph, Helio Castroneves couldn't help but let his mind wander. These moments were his favorite with wingman Sam Hornish Jr.

The Team Penske duo dominated the early stages of Sunday's IndyCar Series finale at Chicagoland Speedway, running 1-2 for 116 of the first 129 laps. It was a flashback to 2006, when the familiar red and white cars were almost always up front.

"I was kind of thinking about it, running with him," Castroneves said. "We work so well together -- he's so incredible on the ovals.

"He'll be missed."

That was the epilogue on the Peak Antifreeze Indy 300 for Team Penske. As it turned out, the familiar No. 3 of Castroneves and No. 6 of Hornish failed to finish where they ran for much of the day on the 1.5-mile oval. The pair led 146 of 200 laps, but championship contenders Dario Franchitti and Scott Dixon took over late, with Andretti Green Racing's Franchitti winning the race and the title when Dixon, of Target/Ganassi Racing, ran out of fuel at the end.

In the immediate aftermath, the Penske boys wondered how their Dallara-Hondas came up short on ethanol ("Dario went seven laps further than Helio and I did. That's 3 gallons more, I don't know anyone that can save three gallons," Hornish said.) but talk soon turned to the future.

Castroneves in the coming months is "Dancing with the Stars," though coming back to his day job in IndyCar next year. Hornish is all but certain to be dancing with fenders in NASCAR in 2008.

Change appears to be coming all over the IndyCar paddock, from the mid-major teams (Hideki Mutoh likely taking Kosuke Matsuura's spot at Panther Racing) to the defending champions (Franchitti is said to be NASCAR-bound, though he has made no public comment), but nothing sounds stranger than the Castroneves/Hornish duo breaking up.

The pair raced as a team for four years, the longest alliance in the series, winning a combined 15 times. Only Andretti Green Racing scored more over that span, though its 29 wins were spread among five different drivers (Franchitti, Tony Kanaan, Dan Wheldon, Bryan Herta and Marco Andretti).

Last year Team Penske peaked, with each driver winning four times and Hornish taking the Indianapolis 500 and the series title. For practically the entire season it was Penske versus Ganassi, a train of red and white cars winning all but two of 14 races.

This year Penske couldn't duplicate the success, with Castroneves winning just once -- at St. Petersburg -- despite a record seven poles. Hornish won in June at Texas but then led just one lap in the next nine races prior to Chicagoland, finishing an average of 10.3 with three DNFs.

Those lean times made the early-to-mid stages Sunday fun, but the day ended in a similar fashion as much of the rest of the season.

"It felt pretty good, but for whatever reason I had the feeling that it was going to be just like it's been the rest of the year -- we wouldn't be able to get the job done at the end," said Hornish, who led a race-high 90 laps. "It was frustrating, because the only time we didn't lead was when we were in the pits or when we wanted to follow Helio and see if we could get a little better fuel mileage. We had a phenomenal car."

When will Hornish be able to say that again? He left Chicago for Talladega, Ala., and two days of restrictor-plate COT testing and has a slate of NASCAR races set for the rest of 2007, trying to get a handle on the heavy stock cars. The 28-year-old continues to say he's unsure what he will do in 2008, but that appears to be more a statement on his Busch/Cup schedule than his open-wheel slate.

Odds are Penske American LeMans Series driver Ryan Briscoe -- who finished fifth at Indy this year in a Penske-owned car -- will be taking Hornish's full-time job in IndyCar. Hornish could be back for a one-off in the 500, still eager to drink the milk again and get a 20th IndyCar Series win.

"That'd be about the best match for me, but we'll see what happens," Hornish said.

What we won't see is Hornish and Castroneves as regular wingmen again.

John Schwarb is a freelance journalist covering motorsports and is a contributor to ESPN.com. He can be reached at johnschwarb@yahoo.com.