The city of Philadelphia is the latest to file suit against Ford Motor Co. demanding that the automaker fix its Crown Victoria police cars, which have been involved in the deaths of at least 16 police officers.

Philadelphia joined lawsuits now pending in at least eight other states. It said taxpayers should not have to pay to improve the safety of the police cars, which are used by about 85 percent of U.S. police departments.

"Despite the lawsuits and deaths of police officers, Ford refuses to independently test their proposed fixes, refuses to pay for the best fix available and the fires continue," Philadelphia City Solicitor Nelson Diaz said.

The fuel tank on the Crown Victoria is behind the rear axle, exposing it to damage in high-impact rear-end collisions. Police cars are at high risk of such accidents since they are often parked on the shoulder of busy streets and highways at accident and crime scenes.

National Highway Traffic Safety Administration last year conducted an investigation of the Crown Victoria and concluded there was nothing inherently wrong with the car.

NHTSA said the car withstood a 30 mph rear-end collision without fuel spillage in excess of established limits. But the city of Dallas said last July that in two 75 mph crash tests, Crown Victorias equipped with an optional "trunk pack" had significant fuel leaks.

The trunk pack provides extra shielding, as do rubber and plastic shields Ford began adding to 2003 Crown Vics' gas tanks.

Philadelphia criticized Ford for charging extra for the trunk pack and for not seeking an independent source to recommend changes to the Crown Victoria.

Philadelphia officials say no police officers have been hurt in their city as a result of fuel tank explosions. But with 700 Crown Victorias in its fleet, the city wanted to offer the best protection available.