BY JOHN CRAWLEY WASHINGTON An accelerating US consumer shift from sport utility vehicles and pickups to more fuel-efficient cars should reduce rollover, but safety experts worry a lighter fleet poses serious risks despite air bags, anticollision systems and other advances. "Shifting to smaller vehicles will make the problem worse,' said Mr Adrian Lund, president of the Insurance Institute for Highway Safety, a group that meas ures crash test performance that is backed by insurance companies. "You're better off in a bigger vehicle than in a smaller one.' Distressed US auto giants are moving to retool plants and leverage operations in Europe, Latin America and elsewhere to get more small cars to American consumers in coming years and meet tougher federal fuel economy standards. US sales are down in 2008 with gas prices above $4 a gallon and consumers caught in a slowing economy. But sales of compacts, sedans and other cars jumped three per cent in June compared with a 19 per cent drop for less efficient SUVs and pickups, according to Ward's Automotive Group. General Motors Corp has ramped up production of its compact Chevrolet Cobalt and the subcompact Aveo and is working on the Volt electric car. Ford Motor Co plans to introduce the Fiesta to the US in 2010. Chrysler LLC has a partnership with Nissan for the Japanese manufacturer to build it a small car based on a Chrysler design to better compete in the market. Popular fuel-efficient compacts and sedans are made by Japan's Toyota Motor Corp. More than 40,000 people are killed annually on US roads in traffic-related accidents. Three-quarters of the victims are in passenger vehicles with two-thirds of them, just under 19,000, in cars. Most were killed in front or side crashes, according to 2006 federal data, the latest available. Fewer "higher riding' truck-style SUVs and pickups driven for everyday use should reduce rollovers, which account for about a quarter of all traffic fatalities, experts agree. But some note that cars are lighter, not as stiff and have less room inside to protect occupants in collisions with other vehicles and objects, such as poles and trees. "When they hit narrow, vertical fixed-object hazards like telephone poles, a frontend collision at higher speeds results in deep intrusion, sometimes resulting in ripping the engine from its mounts and pushing it through the firewall into the occupants,' Mr Gerald Donaldson, senior research director for Advocates for Highway and Auto Safety, an alliance of interests that includes insurance companies. Donaldson said the government must toughen crash tests and finalize a rigorous roof strength standard. Mr Rae Tyson, spokesman for the Transportation Department's National Highway Traffic Safety Administration, said the government is aware of safety group concerns. He added it is too early to identify new trends.