Trip Comp consistantly 16-20% under actual consumption.

[2016 Versa]

The computer in my Versa does the same thing. It's usually anywhere from 7 to 10% optimistic. I do hand calculations at every fill up. I've also got an Ultra gauge. I've done some re-calibration on it and it's usually within 2-3% of actual MPG. Maybe this is Nissan's way of making people who never do the math think that they're getting really great mileage hoping it will get them repeat customers.