Amazing MPG or my fuel gauge is busted

84.9 MPG?? Holy cow, that's great. Be sure to set up an account on Fuelly to help gather consumption data. Here I thought I was doing good at 65 MPG.

 

Indeed. I need to move to Kansas I wonder what grade of gas the dealer put in the first tank?

I just about got 65mpg UK (54mpg US) in London traffic today AND I had it on Eco.

 

Not to revive an old thread, but I seem to be experiencing the same phenomena as the OP.
2017 Prius Two and Still on my first full tank from the dealer. Trip was reset to 0 before I drove away.
So far, I have 225 miles on this tank and gauge is still showing slightly above 3/4 full. Assuming it is 3/4 full and the tank is 11.4 gallons, that means I have used 2.85 gallons. Doing the math, I am getting 78.9 MPG. The display on the trip set is showing I am averaging 62.3 MPG. And here is even more oddity, the display is showing I have 361 miles left to refuel.
I plan on tracking this closely and will update on real world fuel consumption. I am assuming the fuel gauge is not quite 100% correct. Either that or the estimated MPG on the dash is incorrect. Either way, I am incredibly happy. With the A/C always on here in sunny Florida, I would have been happy with 45 MPG.

 

I will give you advice, just as I did with the Original Poster in post #2, never trust any tank your dealer has anything to do with.

 

There are 10 "pips" on your fuel gauge. One is above full another is below empty and 8 are the ones in the middle. So when you are at "3/4" you are down threepips, the first is 1-2 gallons and the second/third are about 1 gallon each. Therefore at 225 miles you are getting between 55 MPG and in the high 60's. Just remember that the computer runs 5-10% optimistic about MPG.

My 2016 Prius 3 says that I am averaging almost 55 MPG in my 8200 miles of use since new (9 months). My purchase records calculate to about 52 MPG.

JeffD

 

LOL! As I was reading through this thread, I was wondering what kind of mileage Gen 4 drivers were getting around Tampa with our traffic lights that are designed to keep people accelerating as much as possible. Then I see that you are in Tampa. I find that I can get great mileage till I get on S.R. 54. Then I get 100 mpg for one minute and then 10 mpg for one or two minutes. Then another at 100 and then one to three minutes at 10-25 mpg. It's like the green light see me and goes, "Here comes Jerry. ... Wait for it. ... Wait for it. ... NOW!!"

So, 62.3 around here is amazing, especially now that it's heating up here.

 

First tank will be inconclusive, has been on my last 2 cars too - fill it up and see what the next one is like. The computer seems to need a second fill to enable it to make a reasonable judgment, and it's about 2% optimistic too. Fuel gauges are only approximations, really too.

Only way is to keep a logbook, spreadsheet or use FUELLY to calculate it exactly.

 

This most likely explains it. I forgot to account for the "past full" since this is a digital display instead of the needle. I will definitely keep records on my refills and mileage and update this after a few re-fuels.

Agreed on the stop lights. I am in the south and those lights on Dale Mabry have never been timed correctly for the flow of traffic. It's almost like they are trying to keep the traffic congested. Thank goodness for "lesser traveled" avenues.

 

As already noted, bad assumption. This is reading more detail out of the gauge than it was intended to provide, and doesn't account for the uncertainties and built-in 'customer expectation management'.

Similarly, Distance To Empty is 'massaged'. It is a simplistic forecast that assumes 'past performance indicates future results', which as the investment house advertisement disclaimers note, is never ever guaranteed. If fact, it is often far off the mark, due to the wide variations in future unknowables. And unlike those investments, this one has some built in safety margin.

 

Got down to 1/4 tank and re-filled. Real world fuel consumption is 58.8 MPG, computer on the dash showed 62.2 MPG. So the computer estimated about 5-6 % better than real world usage.

Still amazing with the A/C on all the time. I am a very happy camper
If I were to estimate my driving, the mileage was about 60% city and 40% expressway/interstate.