Most automakers have agreed to make big SUVs and pickups less threatening to cars. The changes include lowering many full-size SUVs and pickups and putting head-protecting side air bags in most cars and trucks.

The changes would be phased in by the 2008 model year under a voluntary plan, expected to be announced next month. The plan addresses so-called compatibility issues that place people in cars at greater risk of death in front and side crashes than those in light trucks such as pickups and SUVs. In a car-pickup crash, car occupants are 26 times more likely to die than those in the truck; in a car-SUV crash, people in the car are 16 times more likely to die. Front and side crashes between light trucks and cars accounted for approximately 4,000 deaths in 2001.