City auditors have found a new way to save money, but it’s bound to upset the Police and Firefighters unions. They’ve concluded that if the officers leave their police cars (and fire cars) in the municipal parking lot at night, it could save the city $630,000. The cost saving involves 90 police vehicles, from sedans to motorcycles, but also two cars driven by the deputy firefighter chiefs and one driven by an SJFD press information officer.