When cars and sport utility vehicles literally bump into one another in stop-and-go traffic or in parking lots, their owners should prepare for a financial hit that could reach $6,000, according to new tests conducted by the Insurance Institute for Highway Safety. Because SUVs and other light trucks are not subject to the same federal bumper standards as cars, their bumpers generally don’t line up. That means that what should be minor fender-benders can lead to huge repair bills, according to the institute, which is financed by the insurance industry.