Vehicles equipped with automatic braking or front-collision warning are less likely to cause a rear-end crash, according to a study released Thursday by the insurance industry. The Insurance Institute for Highway Safety says automatic braking — which can bring the car to a stop if it senses an imminent collision — can reduce rear-end crashes by 40 percent. Front collision warning — which warns the driver but doesn’t brake — cuts the risk of a rear-end crash by 23 percent. The institute measured the systems’ effectiveness by looking at police records for 7,490 rear-end crashes in 27 states.