Following the lead of many other countries, the Japanese government recently decided to try and boost sales of green cars with a tax reduction. While the definition of a green car varies, the idea behind the tax rewrite was to promote cars that consume less fuel. In Nissan's case, it also stimulated the manufacturer to improve their engine lineup. While only six models from Japan's No. 3 automaker used to be eligible for the eco tax breaks, the lineup now includes 15 models, including the NV200 delivery van. With the reduced tax, a 75 percent reduction in this case, Nissan's vehicles are becoming more attractive to buyers, and the company reported that sales of its green cars went up by 30 percent thanks to the rule during the month of May. Overall, Nissan's sale were up "slightly" compated to a year ago. This is the first increase in 10 months for the automaker, according to Reuters. Similar figures were given by Toyota (a 20 percent increase) thanks to the new Prius and Honda with the new Insight.