While sales of other highly fuel-efficient automobiles are in decline, sales of the Hydro are rising. The Hydro' s manufacturers attribute its success to the Hydro' s price and very low fuel consumption. However, the Hydro is comparable in price and fuel efficiency to its competitors, so it is more likely that its success is due to the fact that people want to appear environmentally conscious to their neighbors.
The Hydro is recognizable as environmentally friendly in a way that its competitors are not is an assumption required by the argument.