A class-action lawsuit has been filed against General Motors Co (NYSE:GM) alleging that the automaker fixed rear-end problems on police versions of the 2007-08 Chevy Impala, but failed to do so for those owned by some 400,000 other drivers.The problem, according to the lawsuit, causes owners to burn through rear tires. The suit was brought on behalf of a Pennsylvania woman who wants GM to replace her potentially faulty rear suspension rods.The suit could cold GM millions of dollars in replacement tires and parts.The lawsuit alleges, "Despite having knowledge of this premature wear problem, General Motors has not recalled the subject cars, which has required class members to pay the cost of fixing the defective spindle rods as well as for replacement tires and realignment."