[QUOTE="SFO, post: 3119818, member: 151825"]Not very. Best to measure miles driven, divided by gallons pumped.[/QUOTE] I've been depending on the MPG readings on my touch screen since 2008 & you say they are not accurate.
My MPG seems to be 1-2 mpg difference from the screen vs what I measured- I stopped keeping track of that a while ago. If you really want to know how accurate YOURS is, then write down the distance traveled and gallons for 5 or more fill-ups and do the math. You don't count the gallons of the first recorded fill (this is your "zero" point). Due to the variations in fill capacity because of the bladder tank, the more fill-ups you use for the calculation, the more accurate the result. It's total distance over TOTAL gallons used. (if you have a half gallon variation at fill-up, 0.5 of 8 gallons is a pretty big error. But that same 0.5 of 50 gallons is much smaller error) Posted via the PriusChat mobile app.
I've been depending on the MPG readings on my touch screen since 2008 & you say they are not accurate.[/QUOTE] He is correct. It's going to be optimistic by roughly 5%. But it's fine for seeing trends. If it reads higher on this tank than the last one, chances are it really is higher. As @mr_guy_mann said, write down the miles and gallons when you fill up. For just one tank, that's going to be even less accurate since the bladder makes it impossible to know if the tank is actually full or not. But averaging it over many tanks will get you very close. (This is for Gen 2. The newer ones don't have that dratted bladder.)
You have been a member of this forum for about TWELVE YEARS and you don't know the answer to that question ?? It depends a little bit on year and model but the general answer is: Not very.
