Sean McLain:

When the Prius first went on the U.S. market in the late 1990s, it was a hit among celebrities like actor Leonardo DiCaprio who flaunted their environmental bona fides with the hybrid gas-electric car.
 The latest version, which hit roads in December last year, is more fuel-efficient than ever, getting 54 miles to the gallon. In Toyota’s home market of Japan, it tops the sales charts. But sales are down in the U.S., as cheap gasoline dent the car maker’s strategy of presenting itself as the leader of an environmentally-friendly future—with the Prius as the vanguard.
 U.S. sales of the Prius are down 26% this year through August.