Yasuyuki Yoshinaga was in a good mood at the early May earnings briefing in Tokyo. The top executive at the maker of Subaru automobiles joked that he would have to wear a helmet on an upcoming trip to the United States. The reason: Dealers were going to hit him over the head for not supplying them with enough of his cars to sell.

Subaru's U.S. sales have almost doubled in the past four years. At the heart of that success is the company's Forester all-wheel-drive sports utility vehicle, which has carved out a following with American drivers for its performance, price and aura of social responsibility.

That has been a key selling point for Subaru, which has marketed itself in the U.S. as the automaker with a conscience. Subaru's "Love Promise," in which it pledges to make "a positive impact in the world," has helped build loyal consumers in states like California, New York and Washington.