[bford]

My wife and I bought a 2013 Prius 2 a couple of weeks ago. We just went through the first complete tank. The dash states that we averaged 45 mpg. I was really hoping that would be higher but its twice what we were getting out of our Camry. Upon further inspection my calculations are showing that we are getting significantly less than the 45 mpg. The dash is saying that we drove 440 miles on the tank, divide that by 12 gallons and you get 36 mpg. This is a far cry from the 45 mpg that the dash is saying and even more so to the 51/48 that the manufacturer has stated. What gives here? Why am I only getting 440 miles to a tank? At 45 mpg i should at least get 540 miles.

 

[Easy Rider]

You can NOT measure gas mileage using the stated capacity of the tank.
How many gallons did you actually put IN the tank when you filled it ?
When the gauge points to empty, there typically is still 3 gallons left; when my C starts blinking the low fuel light, there still is two left.

And......the EPA estimates are just that, an estimate. How you drive and where you drive makes a big difference.

Almost all the cars with in-dash fuel mileage displays end up being 2-4 MPH on the high side.

There are at least a few other owners with your model present on here; let's see what they have to say.

I think you need to go a couple of more fillups and see what the actual mileage turns out to be.

 

[bford]

I put or yet my wife put 11.4 gallons of gas in the tank...we drove 440 miles on that...the display said i had 7 miles to go before empty...when i refilled the tank we put in 11.2 gallons in the tank...so i have no idea how if there is 2-3 gallons left over i would have been able to add over 11 gallons to that.

 

[Easy Rider]

..so i have no idea how if there is 2-3 gallons left over i would have been able to add over 11 gallons to that.

You should NEVER overfill the tank.... on any car.

What does your owner's manual say about fuel capacity?
I'm guessing that it is 13 or a bit more and that when the gauge said empty and near to ZERO miles left, you really had about 2 gallons left.

MOST ALL NEW CARS WORK THAT WAY......for various reasons, not the least of which is to try and "help" you not run completely out of gas.
This is what I was trying to tell you in my first reply.

Your 440 miles with 11.2 gallons is just a hair below 40 MPG.
I think that is right in the ballpark of what you should expect.