The proposed rule would extend the standard currently applicable to passenger cars and multipurpose passenger vehicles, trucks, and buses with a Gross Vehicle Weight Rating (GVWR) of 2,722 kilograms (6,000 pounds) — to cover vehicles with a GVWR of up to 4,536 kilograms (10,000 pounds). This extension would enable the rule to cover most large sport utility vehicles. In addition, it would increase the applied force of the test from 1.5 to 2.5 times a vehicle’s unloaded weight (“strength-to-weight ratio” or “SWR”). Required roof strength therefore would be increased, on average, to 1.64 SWR. However, we view the strength-to-weight ratio in this proposed rule as inadequate, because it does not sufficiently improve the level of roof crush protection available in most vehicles sold today.