This boom-and-bust industrial town is getting another boom--make that vroom--today.

The Detroit Renaissance Grand Prix will be flashy enough to attract worldwide attention--as many as 1,500 reporters and photographers are expected to attend. It will be expensive--about $2.5 million--according to most local estimates. And, considering the multitude of pre-Prix parties held here over the weekend, the event already has yielded lots of fun.

The international car race will not repair this city's recession-wracked economy, though. Nor is it supposed to, according to city and business officials.

"I don't think anybody looks to a Grand Prix race to solve the basic economic problems of the city. That is not the point," says Joyce Garrett, press aide to Detroit Mayor Coleman A. Young.

Events such as the Super Bowl football game last January in nearby Pontiac, Mich., and the Republican National Convention held here in 1980 were expected to attract attention and improve Detroit's image. That is the primary goal of the Grand Prix race, Garrett said.

Patricia C. Becker, a city planning officer, put it this way: "People used to think that walking in downtown Detroit was the same as taking your life into your hands. It's important to get people to come here to see that's not true, to show them that Detroit is a nice, human place to be."

Detroiters have been hearing a lot of that talk recently. They heard it when local boosters were working to bring in the Super Bowl, which yielded $61.8 million in gross revenues for the Detroit metropolitan area. They heard it when the city was going after the 1980 Republican convention, which brought in another $47 million for area merchants. And they heard it in 1977, when builders were putting the finishing touches on the $350 million Renaissance Center--a concrete, glass and steel city-within-a-city that was supposed to spark revitalization of the domestic automobile capital's central business district.

But largely because of Detroit's dependence on the auto industry and that industry's recurrent bouts of economic troubles, none of the spectaculars had much effect--either on the city's image, or on its purse--for very long.

The Renaissance Center, for example, has been losing money since opening in 1977, and lost a total of $66 million in the last two years.

Located at the heart of the 2.59-mile, 20-turn raceway on the repaved streets of downtown Detroit, the Renaissance will be one of the most prominent beneficiaries of the contest. That was not the specific intent of the race's organizers, Detroit Renaissance Inc., a nonprofit booster group primarily supported by Ford Motor Co. and General Motors Corp. But that creates the image of a new savior being called upon to help the original savior avoid disaster.

Hard times have left the Renaissance Center with only about 66 percent of its 328,000 square feet of retail space occupied. The Westin Hotel, the center's star unit, has had a similar annual occupancy rate for its 1,400 rooms. The center's current owners say they needed an average occupancy rate of 75 percent in the hotel rooms and shop space to make money, which raises another point:

A change of Renaissance Center ownership is underway. Ford Motor Land Development, a subsidiary of Ford Motor Co. and a 65 percent owner of the Renaissance property, is getting out. Ford and its 49 partners are turning the property over to a smaller group of investors headed by Theodore Netzky, a 39-year-old, millionaire real estate developer from Chicago.

Neither the buyers nor the sellers are willing to discuss the cost of the deal, expected to be consummated sometime next month. But Ford officials concede that they have taken a bath on their Renaissance investment.

"There was a big cost overrun by about $100 million when the RenCen was under construction," said Allan D. Gilmour, comptroller of the additional money needed. Then, we got into a recession. That . . . clearly has hurt the financial condition of many of the partners, although none of them has gone bankrupt or any such thing as that."

When the new owners arrive, they are expected to make some major changes in the center's operation. For example, according to Richard Routh, spokesman for Ford Motor Land, the center's retail firms will focus more on moderate-priced items. About 25 percent of the center's 88 stores now sell luxury and other high-priced goods, Routh said.

"We are too closely tied to the auto industry for that strategy to work," Routh said. "The auto industry has been having its share of problems and the retail thing, as a result, has not moved along." Routh said the original investors learned that "what works in New York or out West" in terms of generating sales and reviving urban economies "does not necessarily work in Detroit."

Whether or not those lessons have been learned by others here in Detroit, which has a 20.5 percent unemployment rate, is an open question. The race is here, with its glamour, its 29 high performance Formula One cars (most of which have Ford-Cosworth engines, but none of which is a U.S. car, per se), its international celebrities, parties, and its money.

All of the rooms in the Westin Hotel are sold out, as are the rooms in the Pontchartrain Hotel, the Book Cadillac, and other hotels along the raceway. The city has put up $800,000 of the $2.5 million price tag, with the city portion going to repave streets involved in the race. On its investment, the city hopes to bring in $4 million for its estimated 1,500 downtown area businesses, and to recoup $200,000 through taxes generated by Grand Prix sales.

But, as Garrett said, the money today is secondary to everyone except the drivers who share in the contest's $1.25 million purse. The real payoff is that ABC-TV will beam the race and Detroit's other attractions to 44 countries, Garrett said.

"When the Super Bowl was here, our city was on the Today Show, Good Morning America and other network shows that told people Detroit is a really very pleasant place to live," Garrett said. "These are the kinds of events that will help us develop a more diversified economy and to develop tourism, which is an industry that helps people at the bottom of the ladder most graphically," she said.

With today's race--the first of three annual Grand Prix that will be staged here--Detroit will join the ranks of glamorous places like Monaco, San Marino and Rio de Janeiro. The other two U.S. cities hosting Grand Prix include Las Vegas and Long Beach, Calif.

Ticket prices for the Detroit Renaissance Grand Prix range from about $15 to $75, a seemingly expensive diversion for unemployed workers here. But DeLetha Burke, who says she falls into that category, will be at the race anyway.

"This is going to be a show. This is going to be a par-teee. I don't miss good shows. And I sure don't miss good part-teees," Burke says.