The accuracy of the miles-to-empty indicator is quite relative, good enough for you to depend on them. The goal of miles-to-empty indicators isn't to achieve 100% accuracy but to give you heads-up on the need to refuel your tank. In most cases, there are error occurrences up to 2.2 - 3.8 mpg with the least error margin of 0.1 mpg. Learn about how far you can drive on 0 miles to empty.