Once again, the usual suspects (“Who Wants to Be a Millionaire,” “Weakest Link”) have raced to the head of the Nielsen ratings list. But there was a surprise entry, too, though it appeared as No. 16 on the list: NBC’s prime-time coverage of NASCAR’s Pepsi 400 race from the Daytona International Speedway. On Saturday night, it scored a household rating of 6.1/13, the highest in the racing circuit’s primetime history, according to Nielsen Media Research figures. It was NBC’s first telecast of the NASCAR season (the first half of which aired on Fox and FX), and was the highest rated program from 8 p.m. to 11 p.m., outpacing Fox and ABC and CBS. Coverage of the race peaked from 10:30 p.m. to 11 p.m., when the household rating hit 7.4/15. For the record, Dale Earnhardt Jr. won on the track where his father was killed earlier this season. As for the Top 10 Nielsen winners for the week of July 2-8: