From Jayski:

UPDATE: Fox announced record-setting ratings for Cup events this year. Fox reported a 7% increase in ratings to a 6.0 from last season. Fox averaged 9.6 million viewers per race, about 600,000 more than last year. Seven races had record ratings this season: Daytona, California, Bristol, Talladega, Charlotte, Pocono and Sonoma.(News Record)(6-29-2005)
Not the big percentage increases that the IRL is showing this year, but Fox seems happy.