The proposed upgrade, developed by the DOT's National Highway Traffic Safety Administration, would also enhance thorax and pelvis protection for passengers.
"This change in the way new vehicles are tested would take our safety program to a new level and have a dramatic, positive effect on traffic-related fatalities," DOT Secretary Norman Mineta said.
NHTSA estimates the change would save 700 to 1000 lives each year. The agency said in serious side-impact crashes involving at least one fatality, nearly 60 percent of those killed suffered brain injuries.
"We expect that this rigorous requirement will spur the introduction of a comprehensive array of technologies for side-impact protection," said NHTSA Administrator Jeffrey Runge. "The proposal represents a major step toward safer vehicles"
The proposed regulatory upgrade could become a final rule as early as 2005, with a phase-in for all new vehicles beginning four years after publication of a final rule.