I bought a new 2017 Versa about a year ago. I have been tracking my mileage. when I compare what I calculate manually and what the car shows is consistently off by about 3 mpg. I don't understand. When I contacted the dealership about this they tell me it is normal. My daughter bought a Buick and the mileage always calculates correctly, my boyfriend bought a Dodge it also calculates correctly. How does Nissan get away with their mileage being inaccurate?