A molded plastic panel for covering an exterior building wall includes a laterally directed lead fin, a laterally extending groove below the lead fin, and a rearwardly directed middle wall between rows of simulated shingles, all for joining laterally adjacent panels. A side flange extending outwardly of the panel may also be included. The molded plastic panel preferably also includes at least one row of simulated shingles separated by a plurality of gaps each having a randomly varying width in order to camouflage spacings between adjacent panels that change because of thermal contraction and expansion. In a particularly preferred embodiment, the panel body includes a locking tab and a folding flange. The folding flange includes a locking lip for engaging a locking tab on an adjacent panel and a flexible hinge connecting the locking lip to the panel body. The flexible hinge allows the folding flange to be disconnected from the locking tab when replacing a single panel.