Police in Sacramento, California announced Wednesday that they would use $5 million in federal money to begin cracking down on auto enthusiasts who modify their vehicles. The money will be used to form an undercover unit to stop motorists who appear to be driving modified cars.

The concept, which originated in San Diego in 2001, has been spreading throughout California generating significant revenue for the state and local departments. In Santa Fe Springs, for example, twelve officers on Drag-Net duty issued 300 citations and impounded 50 vehicles in just one weekend. Several cities have drag-racing ordinances that allow police to auction off seized cars and keep the profits.

In practice, "excessive exhaust noise" tickets are the most common violation. California law does not require police to measure sound levels objectively. Instead, according to the California Highway Patrol, the "citation is based on officer's judgment.