The novelty is wearing off...

[pearsonrj]

... on my second Gen II - had a 2005 and now a 2008 Touring Package 6.
My fuel economy has drifted lower and lower the longer I have the car. The first 10 or so tanks were in the 45 - 49 mpg range. Recently (28,000 miles on the car) I have been getting 39.5 mpg, for the past 4 tanks. It's been a slow but steady decrease in fuel economy.
It's possible that is related to the new tires I have - standard size but possibly not as low resistance as the OEM tires.
It's possible that it is due to low tire pressure, although I check them about one a month and set to 40F/38R.
It's possible that I am just running out of patience babying the throttle all the time with one eye (unsafely) on the economy screen.
It's likely that my short trips (alot of under 6 mile trips) are causing it, but I was doing that when I was getting 45+ mpg.
I got an average of 48 mpg over 800 miles on a return trip from San Francisco to LA, so I know the highway mileage is pretty good, but the suburban stuff is killing me.

I'm also getting really tired of being overtaken by every freakin' SUV (and car), even though I keep up with the traffic and inevitably we all stop at the same lights 400 yards down the road.

Sorry, had to vent somewhere...

[macmaster05]

Sorry to hear that. Here are some options for you;

- Sell it

but what I would do is;

- Modify it a bit - the prius is a dime a dozen especially in northern ca. Mods will give the car a new look, and possibly feel (depending on what you mod). They will also make your car unique which is something to value.

[Rokeby]

pearsonrj,

Ouch! ~40 MPGs! Something's not quite right.

You've covered many of the typical reasons for reduced MPGs. Many
times folks have reported a -5MPG hit for new tires. Tires do tend to
"wear in" over the first 2-3k miles. So, perhaps a little patience -- or a
long road trip! -- is called for.

Other possible causes:
* a dirty throttle body/air mass sensor.
* a real stretch, but a beginning-to-fail 12V battery could cause the
DC-to-DC converter to be in use overly much. This would require MG1
to be used overly much to generate electricity to keep the HV battery
charge up. More power to generate electricity means less power to
move the car and reduced FE/MPGs.
* maybe a slightly dragging rear brake shoe; which could be the
parking brake -- cable operated -- slightly out of adjustment,

Hope this helps.

[qbee42]

Don't forget the cold weather factor.

Tom

[dogfriend]

Originally Posted by pearsonrj

It's possible that I am just running out of patience babying the throttle all the time with one eye (unsafely) on the economy screen.

This might be part of the issue. Speaking for myself, I find that I get just about the same mileage by driving relatively aggressively (not flooring it, but strong acceleration) as I do by "babying it". The car is actually pretty efficient when accelerating, so I accelerate briskly (i.e. just as fast as the majority) until I get up to speed, then ease back on the throttle and maintain that speed. If nothing else, its more fun to surprise a Chevy Tahoe at a stoplight than to be constantly tailgated.

Don't stare at the economy screen in any event.

Don't tailgate others and try to use the brakes as little as possible. Try to keep your momentum when moving and try to time lights so you don't have to stop at them if possible. Momentum is king. Watch out for momentum thieves™. They suck.

[a_gray_prius]

Originally Posted by dogfriend

This might be part of the issue. Speaking for myself, I find that I get just about the same mileage by driving relatively aggressively (not flooring it, but strong acceleration) as I do by "babying it". The car is actually pretty efficient when accelerating, so I accelerate briskly (i.e. just as fast as the majority) until I get up to speed, then ease back on the throttle and maintain that speed. If nothing else, its more fun to surprise a Chevy Tahoe at a stoplight than to be constantly tailgated.

Don't stare at the economy screen in any event.

Don't tailgate others and try to use the brakes as little as possible. Try to keep your momentum when moving and try to time lights so you don't have to stop at them if possible. Momentum is king. Watch out for momentum thieves. They suck.

Coincidentally, this advice will get you point-to-point faster than everyone else.

[uart]

Originally Posted by pearsonrj

It's possible that is related to the new tires I have - standard size but possibly not as low resistance as the OEM tires.

Hi pearsonrj, what brand/size tyres did you get? If they're relatively non-LRR then yep that could be 5% less MPG. I've heard that the Touring edition uses slightly bigger+wider tyres which usually hits MPG a bit anyway, so yeah the tyres could definitely be an issue. In addition, new tyres of any type seem to cut MPG by another few percent until they're worn in.

Now factor in that your local temperature is probably dropping and there's a few more percent gone. Even worse if your region mandates ethanol blend "winter" fuel as do many parts of North America, take off a few more percent. So yes in my opinion the combination of tyres climate and fuel could very easily account for the approx 15% drop that you've seen.

[Stev0]

Originally Posted by dogfriend

Momentum is king. Watch out for momentum thieves. They suck.

What is this "momentum" that everyone talks about? Is it that imaginary theoretical thing where you drive more than two minutes without stopping? Has that ever actually happened to someone?!?

[Patrick Wong]

Originally Posted by pearsonrj

... It's possible that I am just running out of patience babying the throttle all the time with one eye (unsafely) on the economy screen...I'm also getting really tired of being overtaken by every freakin' SUV (and car), even though I keep up with the traffic and inevitably we all stop at the same lights 400 yards down the road.

Who says that you must baby the throttle all the time? Drive like you are in an SUV and overtake all of the cars ahead of you, if that makes you feel better...

[Genoz World]

this is true. the other day i had my worst tank.........low 40's, maybe even high 30's. I thought a wheel bearing or something was causing drag.....until i started to pay attention to the consumption screen. now i'm back into the mid/upper 40's.

i hear ya pearsonrj.