The car industry has been dreading increases in the required roof strength of their cars for years now. The current regulations are holdovers from decades past, and safety advocates are calling for new standards that would dramatically improve safety, though the industry fears the high costs that will be involved. Now, after a series of previous push-backs of the deadline to October 1, the NHTSA has again failed to submit a final set of roof strength standards.

The reasoning for the delay this time around is the need for further 'regulatory analysis', according to U.S. Transportation Secretary Mary Peters. A new deadline of December 15 has been set, and the regulations are expected to push the required strength standards to 2.5 times the vehicle's weight. The new rules will also be expanded to cover vehicles that weigh up to 10,000lbs (4,545kg). Currently, manufacturers must provide roofs that can withstand 1.5 times their own weight, and the laws only apply to vehicles weighing less than 6,000lbs (2,727kg).

Another major sticking point in the rule-making process is the inclusion of language that would limit the rights of individuals to sue car manufacturers in state court. "This would constitute an unprecedented incursion upon the constitutional rights of consumers," wrote Sen. Mark Pryor of Arkansas, along with two other senators, in a letter submitted on the matter in June. Nevertheless, some factions feel the measure is necessary to protect carmakers from exorbitant jury verdicts, such as the one returned in the notorious $82.6 million Ford Explorer case.

Last month, testing by a consumer advocate safety group called Public Citizen showed that during rollover tests, dummies "were exposed to traumatic impacts that would have been fatal or paralyzing" according to The Detroit News. All of the vehicles involved in the test - six, in total - failed the Public Citizen battery but passed the static test administered by the NHTSA.

Throughout the middle of 2008 the NHTSA had been working on new regulations for roof safety, but it has already missed its own deadlines for their unveiling on two occasions. In May the agency announced it would have the new rules ready, but in June announced the updates would have to wait as legal concerns and practicality issues intervened. Planned restrictions on rollover lawsuits and the actual roof-strength standards themselves are among the provisions still be revised.

NHTSA data indicates increasing roof strength from 1.5 times the car's weight to 2.5 times would only result in a reduction of 13-44 deaths and 800 injuries due to rollover accidents in the U.S. each year, though the cost to the industry would likely number in the billions of dollars. Many consumer safety advocates argue that the tiny improvement in safety warrants even greater requirements, and given the costs involved, it could prove more cost-effective to do so.

Public Citizen feels the roof strength improvements alone are not enough, and that 'dynamic' stress tests should be added to the agency's methodology. "We're in the process of updating our rulemaking and we believe the changes will significantly improve roof strength and safety for the passenger," said NHTSA spokewoman Karen Aldana. "They are criticizing us before our revised standard is even released."