Knock all of the bad (dark-colored) vehicles off of the screen using the police car, fire truck, ambulance, and fire engine. Click on a car to make it drive, and click on a moving car to hit the brakes. Get your cars to the right parking spots for bonus points!
Get the good vehicles to the parking spots, and knock the bad ones off of the screen. Tap on a parked car to make it drive, and tap a moving car to hit the brakes!