A lawsuit claiming that General Motors fixed rear-end problems on police versions of 2007-08 Impalas but not those owned by about 400,000 other drivers  should be thrown out, GM was quoted as saying in a Detroit News article.

GM said it cannot be held liable for damages relating to vehicles produced before the "new GM" was created. The "new GM" was formed in July 2009 in a government-sponsored sale of the good assets of "old GM" out of bankruptcy as part of a $49.5 billion bailout.

GM lawyer Benjamin Jeffers said in a court filing on Aug. 11 that the class-action lawsuit filed by a Pennsylvania owner in June should be thrown out because it attempts "to hold new GM responsible for old GM's liabilities."

New GM said it only agreed to warranty obligations of cars assembled before 2009. The suit "is trying to saddle new GM with the alleged liability and conduct of old GM," the response stated.

The lawsuit argues that the rear-end problems cause owners to burn through rear tires, and that GM should replace potentially faulty rear suspension rods. GM sold 423,000 Impalas over the two-year period. The suit is the latest challenge brought on by owners to automakers, who limit the scope of auto recalls or service campaigns.

The only owner currently named in the suit, Donna Trusky of Blakely, Pa., bought a new Chevrolet Impala in February 2008 and said the tires wore out within 6,000 miles. Her GM dealer replaced the tires and provided an alignment, but didn't disclose the spindle rod issue, she said. According to the suit, GM issued a service bulletin in 2008 for police versions of the Impala.

"Despite having knowledge of this premature wear problem, [GM] 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," alleges the lawsuit that was filed last week.

GM's legal response says the issue is not that the spindle rods were manufactured incorrectly, but that the design was the problem. That, GM says, should prevent the lawsuit from going forward.