Sales for Nissan North America, which has plants in Smyrna and Decherd, were up 11% in June. That’s better than the overall national figures for auto sales that went up by only 7 percent. Nissans improvement comes despite the squeeze that many Japanese automakers felt after their nations earthquake and tsunami. Honda and Toyota didn’t fare as well. Those companies saw losses of more than 20 percent. Volkswagen, which recently opened a plant in Chattanooga, saw strong gains. The company posted a 35 percent sales increase over June of last year.