New owner needs help...

I can drive as much as 160 miles and still show full, so do not take too much stock in 'it showed full'.
I would fill it, zero a trip meter, and reset the MPG on the display then see if it was really doing that poorly.

OBDII Code P1121 TOYOTA PRIUS - Coolant Flow Control Valve Position Sensor Circuit Stuck | Engine-Codes.com

I run AC in MS year round, it lowers my MPG to about 42 above 95F

 

I only get 42 mpg in my '07 Prius on average so we're not that far apart. If you are only driving 5 or 7 miles to work one way then the first 3 or 4 miles are likely going to get a LOT lower mileage as the Prius gets lower mpgs as it warms up so for a third to half of your commute your are getting much lower mpgs which will reduce the average overall. I'm saying that, under the circumstances, your mileage isn't really that far off.

Take the car out for a hundred mile drive and watch your overall milage go back into the 40's. I think your battery is fine and the mileage that you are getting for the type of driving that you are doing is just about right.

 

Yup, the combination of a relatively short drive and the air cond. is
a MPG killer. And your 12V battery is weakish, though not needing
replacement just yet.

Although typical 12V battery service life is ~4 years, lots of
posts/threads point to service in long term high air temps like in
AZ reduce that significantly.
(Separate issue: this may also be true of the HV battery.)

My daily commute on urban streets is 26 mi. round trip and with
careful driving and a ScanGaugeII has produced 50.2 MPG over
65K miles... but then I intentionally use heat/air cond. very little.
That's twice you daily miles, but the extra miles are qith a fully
warmed up engine/cat. converter... a big difference.

What tires are you running...
how old are they? ...
at what pressure?

Tires with <3K miles will reduce MPGs by ~3,
MPGs are improved ~3 MPG at PSIs of 43 front/40 rear.
(Don't worry, these are well below sidewall max pressures.)

 

We have a similar problem in the winter when we have to run the defroster on a cold ICE to keep the windshield clear. 60mpg doesn't do you any good if you can't see.

The other side of your situation is that if you are uncomfortably warm then probably so is your battery. Running the AC makes you & the battery feel better. Batteries are less efficient when very cold or very hot.

What is your tire pressure? Increasing to max sidewall will help.

Do you have LRR tires on the car?

 

Yes, very little maintenance to do.

http://www.toyota.com/t3Portal/docu...MS0012/pdf/01omsour/2005/schedmai/51w1smt.pdf

I do not know your mileage, so I can't give a page number.

One item I would add, would be a Transaxle fluid change (about $100, if done by the dealer) with WS ATF. It is not in Toyota's schedule, but at 30,000 miles and then every 60,000 miles after that is a good idea to clear out metal bits before they short out the Motors. Expect the dealer to claim that it never needs changing, and just be firm that you want it done.

 

PDF page 17, manual page 14

then at 90,000 have the ATF changed, not just inspected.

(I spent 14 years in Elko NV, I hope you like the state)

 

Ah, I was on the '10 months of snow' end of the state, so MS is a change.