The National Highway Traffic Safety Admin. asks Congress for more time to write new roof-strength rules, a standard last updated by the nation’s top safety regulator in 1973.

“We must ensure that any final rules we issue are as successful as possible,” Department of Transportation Secretary Mary Peters says in a statement yesterday. The DOT oversees NHTSA. “Accordingly, we have informed Congress today that we need more time to complete a new roof-strength standard that effectively protects motorists.”

NHTSA missed a self-imposed deadline of July 1 for the new rule, which was expected to raise roof strength from 1.5 times the weight of a vehicle to at least 2.5 times, and the timetable was extended to Oct. 1.

In addition to increasing the roof-strength ratio, NHTSA was expected to place the mandate on a broader range of vehicles and increase the distance between a driver’s head and the roof so an adult-sized male would not become stuck after a rollover crash. NHTSA thinks the tougher standard will save 44 lives and 800 injuries annually.

Safety advocates want even tougher rules, and while the auto industry supports NHTSA’s proposal, which dates back to 2005, manufacturers say data and analysis does not demonstrate a need for roof strength above 2.5 times.

In fact, the Alliance of Automobile Manufacturers, a group representing major U.S. auto makers in Washington, says any rule above 2.5 times could negatively affect safety by forcing auto makers to make stronger roofs sooner than present technology may allow. It also would decrease fuel efficiency, the group said in a statement to Congress earlier this year.

AAM further says prevention of rollovers altogether, through greater seat-belt use and a broader proliferation of electronic stability control, represents the most effective way to reduce injuries or death in such crashes.