Ford Motor Co. plans to enhance the roof strength of some pickups and sport utility vehicles beyond standards proposed last year by the government, the automaker has told regulators.

James P. Vondale, Ford’s director of automotive safety, said in a Nov. 20 letter to the National Highway Traffic Safety Administration that enacting the NHTSA proposal would lead to “many future vehicles” having roofs comparable in strength to the Volvo XC90 SUV. That vehicle can withstand 3.5 times its own weight.