Question: The 2003 Auto Club 500 was won by the 2004 champion of what?
Context: The Pepsi Max 400 was a NASCAR Sprint Cup Series stock car race held annually at the Auto Club Speedway in Fontana, California.  It was the second of two Sprint Cup Series races held at the Auto Club Speedway (the other being the Auto Club 500) and in 2009 and 2010 it was run in October as part of the Chase for the Sprint Cup. The 2009 Auto Club 500 was the second race of the 2009 NASCAR Sprint Cup season.  the 500 mi race occurred on February 22, 2009, at the 2 mi Auto Club Speedway in Fontana, California, 60 mi from Los Angeles and was one of the cleanest races in the history of the track with only one caution for an on track incident out of all 250 laps.  Fox broadcast the race beginning at 5 pm US EST with radio coverage on MRN (terrestrial) and Sirius XM Radio (satellite) starting at 5:15 pm US EST.  The race started at 3 pm local time, and run into prime time, counterprogramming against the Academy Awards. The 2008 Auto Club 500 was the second race of the 2008 NASCAR Sprint Cup Series, and started on February 24, 2008, at Auto Club Speedway of Southern California in Fontana, California, a suburb of Los Angeles.  The race was telecast on Fox starting at 3:30 PM US EST/12:30 PM PST, with MRN and Sirius Satellite Radio's broadcast starting at 2:45 PM EST/11:45 AM PST.  Rain stopped the race on Lap 87 and the race would continue on Monday, February 25 at 1 PM US EST/10 AM PDT. The Auto Club 400 is a 400-mile (643.737 km) Monster Energy NASCAR Cup Series stock car race held at the Auto Club Speedway in Fontana, California.  Prior to 2005, the race was held in late April or early May, and until 2010, the race was run at a length of 500 miles.  When the NASCAR Realignment of 2005 was made, the race was moved to February and the week following the Daytona 500.  The February date stayed until the 2011 season when the date changed to March.  After being pleased with the results of the shortening of the track's former fall race date, the Pepsi Max 400, from 500 to 400 miles Auto Club Speedway decided to do the same thing to its spring race. The 2007 Auto Club 500 was the second race in the 2007 NASCAR Nextel Cup season.  It was held on February 25, 2007 at Auto Club Speedway in Fontana, California. The 2003 Auto Club 500 was a NASCAR Winston Cup Series stock car race held on April 27, 2003 at California Speedway in Fontana, California.  Contested over 250 laps on the 2-mile (3.23 km) asphalt D-shaped oval, it was the tenth race of the 2003 NASCAR Winston Cup Series season.  Steve Park of DEI won the pole.  Kurt Busch of Roush Racing won the race.  This was also the last race for Jerry Nadeau.  His career ended with an injury during practice at Richmond The 2010 Auto Club 500 was a NASCAR Sprint Cup Series race held on February 21, 2010 at Auto Club Speedway in Fontana, California.  Contested over 250 laps, it was the second race of the 2010 Sprint Cup Series season.  The race was won by Jimmie Johnson for Hendrick Motorsports.  Kevin Harvick finished second and Jeff Burton clinched third. Kurt Thomas Busch (born August 4, 1978) is an American professional stock car racing driver.  He currently drives the No. 41 Ford Fusion for Stewart-Haas Racing in the Monster Energy NASCAR Cup Series.  He was the 2004 NASCAR Nextel Cup Series champion.  Busch is currently a free agent for 2018, but Stewart-Haas Racing expects him back.  He is the older brother of 2015 NASCAR Sprint Cup Series champion Kyle Busch.  The brothers are second-generation racing drivers; their father, Tom, won several NASCAR-sanctioned events. The 2004 Auto Club 500 was a NASCAR Nextel Cup Series stock car race held on May 2, 2004 at California Speedway in Fontana, California.  Contested over 250 laps on the 2-mile (3.23 km) asphalt D-shaped oval, it was the tenth race of the 2004 NASCAR Nextel Cup Series season.  Jeff Gordon of Hendrick Motorsports won the race. The 2006 Auto Club 500 was the second race of the 2006 NASCAR Nextel Cup season.  It was held on February 26, 2006 at Auto Club Speedway in Fontana, California.
Answer: NASCAR Nextel Cup Series