I don’t think people expect a perfect estimate, they just expect it to be less than 2 gallons/40 miles off.From a programming point of view, there are way to many variables including your changing driving habits, temperatures, winds, road terrain, load weight, etc. to make a perfect "estimate" as you are driving over a few days or weeks. That said, they may be able to make it better with a software update, but it is still just an estimate based on conditions over the past xxx miles of your driving.
Sponsored