Police converged on the parking lot around 10:15 p.m. Sunday where they discovered about 150 cars gathered. When police appeared, they scattered, Showalter said.

Police searched about 85 cars -- most of them Hondas and Acuras -- citing around 50 for illegal engine modifications and impounding 11 because the vehicle identification numbers had been tampered with.

Confronted by police, many owners insisted they don't race their modified cars, Showalter said, chuckling at the thought of the pricey, tricked-out engines. "This isn't for driving to and from work."

Showalter said the custom shops that sell and install the parts are difficult to target. Making the modifications usually is not illegal, he said, but driving the modified cars on the road is.

What's more, racers who can't afford the expensive modifications often finance their hobby through auto parts theft or insurance fraud.

The Riverside department was one of three area police departments last summer to receive two-year $400,000 state grants to combat street racing. Some of the money has been used to train officers to spot illegal modifications.

About 35 officers participated in Sunday's raid, including members of the San Diego, Irwindale and Ontario police department Drag-Net programs.

Cpl. Jeff Higbee, coordinator of street racing grants in Ontario, said the public often does not appreciate what a serious problem illegal street racing has become.

"They have the vision of 'American Graffiti,' " he said. These days, he said, "It's a lot different than the 11 cars going out in the middle of nowhere and getting off a race or two."

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