For those who pull away from the pump with their gas tank caps on their trunk lids, Ford Motor Co. has begun to make good on a 2006 promise to get rid of the caps on its entire model lineup.Jettisoning the pesky caps will become most apparent in the new 2009 F-150 pickup truck, Ford’s top-selling vehicle, which was unveiled this week at the North American International Auto Show. It will hit showrooms in the fall.

The capless refueling system already is available on the 2008 Ford Explorer sport utility vehicle, and it is coming to the 2009 Flex crossover and Lincoln MKS luxury sedan, said Matt O’Leary, chief engineer on the pickup.

The system, which came from Ford’s NASCAR racing experience, first appeared on the 2003 Ford GT sports car.

It has two small spring-loaded tabs that pull back a flap inside the fuel filler neck as the nozzle hits them. When the nozzle is pulled out, the flap closes.

In addition to the convenience factor, the capless system also has environmental benefits, O’Leary said, by limiting the escape of gasoline vapors.