The Nissan Sentra is a mid-size sedan with a front-located engine and front-wheel drive. Over the years, the Sentra has changed in size, first from a sub-compact to a compact car, and finally to its current classification as a mid-size sedan beginning with the 2007 model year. The four-cylinder engine makes the Nissan Sentra very fuel-efficient. Combined with a comfortable seating capacity, this makes the Sentra a popular choice for couples or small families.