Decrease in MPG as car ages?

whoa. Please advise.

 

Some people have reported that a failing starter battery (not the traction battery) has this effect. Does your Prius have the original battery?

 

If anything, my '04 is getting *better* MPG at 130K, esp. as this
summer kicks in and on the new Michelin EnergySaver a/s tires.
Finished a run to the Cape and back just today, showing just
over 70 MPG and much of that was highway at 60+ mph. Traction
pack is fine, as recently checked, and its 12V is still the
yellowtop from elearnaid which I don't expect to poop out
for a good couple more years.
.
_H*

 

Before you replace the battery check the voltage & report the readings. For the record, I expect your 6 year old battery to be weak but KNOW why you're swapping out a part, don't GUESS or HOPE that will solve your problem.

 

+1

What tires do you have now (size, make and model please) and what pressures do you keep them at? Perhaps you've changed them to something w/higher rolling resistance?

Yes, the HV battery does lose capacity over time but government long term tests didn't show significant mileage changes, at least not on Gen Is. See http://priuschat.com/forums/gen-ii-...-miles-w-dropping-mpg-common.html#post1014257.

 

that's excellent H! any tips? we usually get low 60's on the way down and high 50's on the way back. factory tires and 55-65 mph. mostly 65. thanks!

 

When is the last time you checked your alignment?

 

The new tires must "break in" before they will yield good mileage.
It's time for the spark plugs to be checked/replaced.
Engine air filter ok?

The Prius is good at not aging fast, but even it requires maintenance eventually.

 

Very late answer to bisco and anyone else curious: This may help,
as I hadn't finished writing it at the time the topic came up...
.
_H*

 

12.5 seems pretty low. I think it is supposed to be 12.8.

 

Yes I am curious enough to start a new thread here:
http://priuschat.com/forums/gen-ii-...y-mode-lower-speeds-50-55mph.html#post1139988

Please kindly reply questions asked there. Thanks!

 

I think you need to turn on the headlights and see it that 12.5 V imediately drops below 12 V. I new fully charged battery would be closer to 13.2 V with the car off.