Abstract: A molded plastic fuel tank filler neck cap includes a closure portion having an axially inner end for engaging and closing the filler neck, and an axially outer end. The cap further includes a shell providing a hand-grip cover, the shell and the closure axially outer end being rotatably fastened together by a retainer ring. The shell includes a depending radially outer annular skirt having a radially extending flange adjacent its axially inner edge. The flange provides a peripheral, axially outwardly facing surface. The ring includes a radially outer, axially extending portion which provides an axially inwardly facing surface for engaging the axially outwardly facing surface of the flange. The axially inwardly facing surface extends interruptedly peripherally about the ring to provide engaging segments and clearance segments. The ring includes a plurality of radially and peripherally extending slots which are axially spaced from the interrupted axially inwardly facing surface.