Tens of thousands of spectators trooped through crowded paddocks and grandstands, clutching ear plugs and checkered flags. Auto-racing teams praised the exciting twists and straightaways through roads normally choked with harried commuters.

And the cars, intricate and sleek, careened through downtown Baltimore, blazing what many hope is a new tradition in the city's collective life.

The inaugural Baltimore Grand Prix concluded Sunday, impressing spectators, particpants and city officials. Perhaps it was only appropriate that the winner of the race — which followed months of elaborate preparations and traffic-snarling construction — was named Will Power.

Power, who has won more competitions this year than any other driver, gushed that Baltimore's three-day racing festival was "very impressive for the first year."

"They've put on the best race we've had all year," he said of the contest that lasted two hours and two minutes. "This is what Indycar needs."

Although final measures of the race's economic impact, and the cost to the city coffers, could take days or weeks to tally, officials declared the event a success. The Baltimore Police Department estimated that 15,000 attended Friday and 40,000 Saturday. No official count was available Sunday, but organizers estimated that attendance topped 150,000 for the three-day event and said police lowballed crowd counts for the first two days.

Mayor Stephanie Rawlings-Blake, speaking at a news conference after the race, denounced those who had doubted the event's potential.

"The naysayers certainly had their day," she said, then paused for effect, "until the race started."

"Anytime you do something big you take a risk," said Rawlings-Blake. "I had the opportunity to let Baltimore shine."

The city, which invested more than $6.2 million to prepare roads for the event, has inked a tentative five-year contract with Baltimore Racing Development, a group that conceived the city's grand prix. Indycar officials plan to release next year's racing schedule later this month.

Jay Davidson, president of Baltimore Racing Development, said "the weekend exceeded our wildest expectations."

Spectators savored the novelty of seeing cars fly through city streets at speeds approaching 190 miles an hour.

"It's just as exciting when they come by for the 70th time as when they went by the first," said Albert Whitelock of Severna Park, who viewed the race from Pratt Street, where cars hit the highest speeds along a long straightaway.

"It never gets old," Whitelock shouted over the roar of the engines. "To have this in Baltimore, it just puts the whole city in a different light."

Steve Thomas weaved through the crowd gripping a unique souvenir — a used tire.

The 21-year-old college student from Westminster picked up the tire from the Baltimore Convention Center, which housed a paddock of race cars, transport trucks and equipment.

The tire was covered with gobs of rubber, which had melted from the heat of the race and congealed again, and emblazoned with a driver's autograph in white ink.

"Honestly, I don't know who it was," said Thomas, a new convert to Indycar racing, pointing to the signature on the tire.

Longtime racing fans said they had grown smitten with the city but felt that race organizers needed to work out a few bugs.