New York ? Cadillac tuned up a classic 1959 Eldorado and borrowed a 30-year-old rock anthem for its new Super Bowl ads.

Pop star Britney Spears reprises Pepsi’s jingles dating as far back as the 1950s. And tax preparer H&R Block plays a version of an aptly named Beatles’ tune from 1966 in its first appearance in the big show.

General Motors' Cadillac division hopes to broaden its customer base with an ad that shows a 1959 Eldorado with signature tail fins alongside pricey new Cadillac models. The Super Bowl has become known as a showcase for advertising. Some people consider Super Bowl ads part of the entertainment.

Some Super Bowl advertisers are hoping to score points Sunday on television’s biggest and most expensive attraction of the year by stirring warm nostalgic feelings among the 130 million viewers expected to watch at least part of the NFL championship game.

Ad salesmen at the Fox network, which is broadcasting the game between the St. Louis Rams and New England Patriots from New Orleans, may be pining for yesteryear, too.

The recession, a pullback in ad spending and competition for ad budgets from the Winter Olympics in Salt Lake City starting five days later have depressed Super Bowl ad prices. Some marketers wonder if Americans are ready to party after the Sept. 11 attacks and amid war in Afghanistan.

Ads for this year’s game fetched an average price of just under $2 million for each 30-second spot, Fox officials said, down from the $2.1 million average CBS got a year ago. Both averages fell short of the record $2.2 million average that ABC said it got in 2000, when 17 dot-com advertisers flush with venture capital bought 40 percent of the commercial time.

But even at the relatively low price, the Super Bowl towers over the $400,000 that ad buyers say top-rated series shows get.

Nielsen Media Research said “Friends” has been the highest rated prime-time series so far this season with a 15 rating; last year’s Super Bowl had a 40.4. Each rating point represents about 1.06 million homes. Nielsen estimated the Super Bowl’s average audience was 84.3 million, versus 24.3 million for “Friends.”

A Danny DeVito figure hawks a can of reformulated Lipton Brisk in one of several Pepsi commercials set to air during Sunday's Super Bowl. Pepsi has bought three minutes of ads during the game.

Besides the big audiences and high prices, the Super Bowl has become known as a showcase for advertising.

“It is the most heavily viewed program of the year, and some people will be watching just for the ads,” said Gretchen Hoffman, a marketing executive for Universal Orlando Resort, a first-time Super Bowl advertiser.

Past Super Bowl sponsors skipping the game this year include MasterCard International, Volkswagen of America, Cingular Wireless and Electronic Data Systems.

EDS, the technology consultant from Plano, Tex., had run ads featuring wandering cats and stampeding squirrels in the past two Super Bowls. This year, it bought 58 commercial spots over 17 days in the Olympics telecast to provide more detail on its services.

“The Super Bowl established who we are,” said LaWanda Burrell, a top advertising executive at EDS. “This year we want to get more into the specifics of what we are.”

Critics say the Super Bowl is a huge risk for smaller marketers.

“Brands are developed by touching consumers again and again in their daily lives and not with just one commercial,” said Don Pettit, president and chief executive of Sterling Group, a brand consulting firm.

A test subject is unconscious after being struck by a dart from a blow-gun in this Quizno's commercial.

Brewer Anheuser-Busch will be the biggest sponsor this year with five minutes of ads. Pepsi has three minutes, including one minute for reformulated Lipton Brisk. A half-dozen studios will pitch their movies.

General Motors’ Cadillac division hopes to broaden its customer base with an ad that shows a 1959 Eldorado with signature tail fins breaking from the pack and driving past pricey new Caddy models. The ad features the Led Zeppelin’s energetic “Rock and Roll” from the early 1970s.

In a 90-second ad for Pepsi, Spears dresses for the period as she performs Pepsi jingles from generations past. She is a sweater girl in a 1950s diner pitching Pepsi as the drink “for those who think young.” In a modest one-piece swimsuit in a beach scene set in the 1960s, she sings Pepsi has “the taste that beats the others cold.”

Dawn Hudson, a top marketer for Pepsi, said the ad would resonate with older viewers who remember the original ads as well as youngsters “who like it because it is retro and hip.”

Kansas City, Mo.-based H&R Block has bought the rights to feature a re-recorded version of the Beatles’ “Taxman,” and will feature it in an ad that pitches Block as the place to go for those bewildered by the new tax laws.

Other advertisers include Taco Bell and Quizno’s, a toasted sandwich chain based in Denver. The online broker E-Trade and online job sites Monster and Hotjobs are back, survivors of the dot-com bust, along with Internet portal Yahoo!.

Tobacco giant Philip Morris and anti-smoking campaigner the American Legacy Foundation return with messages against smoking. The White House is airing a pair of commercials warning that buying illegal drugs could finance international terrorists.

Britney Spears goes hippie in a Pepsi commercial. Spears recreates Pepsi jingles going back to the 1950s in Sunday's commercials.