With its lean, muscular lines, Mitsubishi's Montero Sport has long been one of the best-looking SUVs. Lately, however, Mitsubishi has been working to prove that beauty is more than skin deep. Last year, the Montero Sport benefited from interior refinements and a coil-sprung rear suspension. For 2001, the body has been re-engineered for greater safety, and both available engines massaged for lower emissions with better fuel economy. Headlining the changes, however, is a new performance-leader 3.5XS model, which combines Mitsubishi's biggest engine with a unique exterior appearance and a surprisingly moderate sticker price.