The auto industry has pledged to work with federal regulators to reduce injuries resulting from collisions between sport-utility vehicles and cars.

The effort could lead to the "development of voluntary standards, such as those previously developed for side air bags," two industry groups said in a letter sent Thursday to Jeffrey W. Runge, administrator of the National Highway Traffic Safety Administration.

The letter was signed by Brian O'Neill, president of the Insurance Institute for Highway Safety, and Josephine S. Cooper, president and chief executive of the Alliance of Automobile Manufacturers Inc.

The letter says it is too early to predict what automakers will do to increase safety. But Runge and others have expressed concern about the dangers SUVs pose to smaller cars. In crashes, sport-utility vehicles can strike cars above their bumpers. SUVs also have high rollover rates.

Last month, Runge said the rollover fatality rate for SUVs is triple that for passenger cars, and -- referring to SUVs with poor safety ratings -- said, "I wouldn't let my kid buy a two-star rollover vehicle if it was the last one on Earth."

The automakers promised to address those issues in the letter.

Ann Smith, a spokeswoman for DaimlerChrysler AG, said yesterday that the letter followed a pair of technical workshops earlier in the week in Washington.

The auto industry will form teams to study the impact of front-to-front collisions and front-to-side crashes, Smith said.

She said the industry wants to look into "what happens when vehicles of different sizes hit each other."

The Washington-based alliance is a lobbying group that represents 10 automakers, including General Motors Corp., Ford Motor Co. and DaimlerChrysler. The insurance institute is a safety research group financed by auto insurers.