This spring, Nissan has more to celebrate than just the arrival of warm weather. Instead the automaker is celebrating yet another sales increase. April sales in the U.S. are up 23.2 percent with an impressive total of 87,847 vehicles sold. Compared to last year's April sale of 71,329 units, this is quite the increase. Let's take a look at the contributing factors that are leading to Nissan's success.