New to me Gen 3 is not living up to fuel economy expectations

yes, in most instances, gen 3 does a bit better. they accomplished that by programming the software to do a bit of pulse and glide.
but on used cars, there are so many potential issues

 

See post #15. And #11...

 

I would check the fuel trims next.

 

Long term trims should be zero or darn close to it. This is true for any fuel injected gasoline car. Short term trims don't mean as much but can still add info to other diagnostics.

*shrug*
To me, it sounds like a pretty normal 3rd generation car with the hybrid battery starting to go soft.

 

I've never used the Dr. Prius app, so I have nothing to offer there.

I don't know that I would spend the money trying to prolong a battery that is already 13 years old. I'd always understood that technique as something best started when the car is fairly young.

From everything I've read, the 2nd generation cars were a little overbuilt and tended to last longer as a result. The 3rd generation cars seem to have been done on a tighter budget, and I certainly see lots of them getting multiple expensive problems around their 15th birthdays where the older ones leaned closer to 20.

Good luck with it!

 

You are getting about the same MPG as my 2011. I gave up trying to get it higher, just waiting for the hybrid battery needing to be replaced.