Curious - Why mileage difference between 2005 and 2013 Prius?

Everything being equal (including driving routes and typical trip distances), the 2012-13 should be slightly better than the 2005.

Sift though this list of ideas:
Fuel economy complaints/queries? Please copy, paste & answer these questions, esp. if you're new | PriusChat

Check also for brake drag, which ought to be noticeable as unusually warm wheel hubs.

 

There are very tiny situations where Gen 2 is more fuel efficient than Gen3, mostly 55 to 60 MPH range. If that is where you drive, it is hard to beat a Gen 2; by 70 MPH, the Gen 3 wins big.

 

I never heard that. I didn't own a Gen 3 though.

 

This chart shows engine efficiency, the 1.8 is more efficient over a broader range of RPMs, but the are spots where the 1.5 is as good.



I did not suceed in googling the Gen 4 graph

 

I believe it also takes some hypermiling skill, more than the average driver.

But didn't all the hypermiling Japanese commuters setting tank miles records, do them in Gen2s?

 

there is something seriously wrong with your car, and possibly your daughters, if, under the exact same conditions, they are getting 10 mpg less than your 2005.

but see post number two, because it is almost impossible to replicate conditions.

start with tire model and pressure, and go from there.

 

Just grasping at straws: the 2005 has a semi-clogged engine air filter, the computer compensates, and it's behaving like a lower displacement engine??

The outlier seems to be the 2005, that very good mpg for second gen.

 

you mean i can get better mpg's with a clogged air filter?

 

I have to ask. Is this the mileage from the car's reported usage or your own empirical measurements? 55 -57 mpg for a gen 2 is extremely high to be normal for anything other than an unusual trip somewhere in certain conditions. Are you saying you've driven said gen 2 for many thousand miles and your average is 55 - 57 mpg? I've been driving my '07 gen 2 for about 16 months and a little more than 25K miles and I am averaging 45ish mpg (calculated at the pump and averaged since I bought the car), which I consider both normal and good.

 

... but a filter that clogged should increase manifold vacuum and pumping loss, losing some of the Atkinson-cycle benefits that produced the Prius MPG improvement.

 

For the Gen 3, the above map is for a fully functioning EGR. Gen 3 uses 22% EGR to improve fuel efficiency and reduce knock with regular gas. With 50% reduced flow rate the MPG should drop by at least 11%. With 100% blockage MPG should drop by at least 22%. Also consider the fuel economy impact when ignition timing is retarded b/c of knocking.

 

I think we may have lost the OP.

 

It’s only two days, give them three months

 

My 2007 (Gen 2) Prius returned an average of 56mpg over the 4 years I owned it - measured by fuel fill-ups, not the display - and in summer would routinely beat 60mpg, dropping to tanks of 52-53 in winter. My 2011 (Gen 3) managed an occasional 60+mpg tank in summer, and a steady 51-52mpg in winter, for an average of 54mpg by the time I replaced it in 2014.

The drop in mpg in the Gen 3 was not startling, but it was notable and disappointing. However, even at worst it did not return a sub-50mpg tank.

In 2014 I got another Gen 3, and that also averaged 54mpg, though it did produce a few sub-50mpg tanks. It also returned a summertime average of 62mpg over 4 years.

 

I knew a guy who owned a Gen 2 and totalled it. He bought another new one the same year and he said it never got the same mileage as his first one.