Dramatic Drop in Fuel Mileage - Please help

I have a 2004 Prius, Option 9, with about 35K miles on it. I've been through two winters and two summers, this one is the third summer. It has been pretty consistent with mileage, getting between 47 and 52 all the time. My high was 57. Now, the last three tanks, my mileage has dropped to 38-40. I'm shocked - because I already do all the things, driving style, A/C control, yada yada to get as much as I can. Here in VA with a long commute on the highway at high speed - this is about as good as it gets (47-52).

A couple things have changed inregard to the car. I had a very poor experience with a dealer, not my normal one, who did the second recall for the computer - reflash, and alignment, etc. Right after that, I got about 50mpg so I didn't think much of it. Almost on top of that, I bought the Goodyear Comfortreds, based upon all the good comments here. I run them at 44 and 42. While I also have trouble filling the bladder, I am patient and top it off. These numbers aren't the MFD numbers - they are calculated. The MFD numbers have also lately become far less accurate. Lastly, I installed the BT Tech brace. That helped the handling with the Comfortreds which I find to be a bit problematic. While I did not like the Integrities, the squashy sidewall on the Comforttreds, even at these inflation pressures, cause some oversteer that I don't like. I'll live with it.

Anyone have any idea what might be happening here? Perhaps the battery is requiring charging more than usual? Help!

 

<div class='quotetop'>QUOTE(efusco @ Jun 22 2006, 12:42 PM) [snapback]275289[/snapback]</div>

HI Evan - thanks for responding. I've been running then about 2K miles or just a little less. I check the air pressure relentlessly in hopes of finding a low tire or something, nada. I have not had it realigned since putting them on since I had it aligned just before, but with the way it handles, I will definitely do that because the last alignment was way off and the change was dramatic after it.

Parking brake is okay and I'm sure the defroster is off. Perhaps the alignment. OR - maybe the A/C needs to be recharged or checked? That would make it run more than it has the past two summers. Anyone have any bad experiences with the reflash? I kind of counted that out, but maybe should not have. Thansk again Evan!

<div class='quotetop'>QUOTE(mikepaul @ Jun 22 2006, 12:46 PM) [snapback]275291[/snapback]</div>

I wish I had gotten that, but didn't. I got the tires through tirerack and had them mounted locally. For alignment I usually go to the local NTB, and yes, spend my hours waiting for it to be done as well! I think that's my next stop, and as Evan also pointed out - I'll check the oil level again. This dealer that serviced my car was particularly bad - destroyed my seats, didn't do the TSB on the fuel filler, etc and didn't rotate the tires per the 30K. I won't go back - but I will check the oil again!

Thanks!

 

<div class='quotetop'>QUOTE(richard schumacher @ Jun 22 2006, 03:36 PM) [snapback]275388[/snapback]</div>

HI Richard,

Thanks for your reply. I've used the same gas station all the time I've had the Prius - at least 90% of the time and all these tanks are the same. So - yes they went to Ethanol, but because it is a warmer climate here this time of year, my gas mileage is better than the winter (where it is cold enough to need to run the heater and the ICE). That's kind of why I was so surprised to see the mileage drop like a rock from one tank to the next.

I don't top off to the point of runover, or even to get the gas up far enough to see it or hear it. It really needs to have the filler tube updated, but the dealer doesn't seem to get it. I do try to fill it with what I think the mileage would indicate should go in and that works without saturating the canister.

Thanks!

 

<div class='quotetop'>QUOTE(HokieHybrid @ Jun 22 2006, 05:26 PM) [snapback]275448[/snapback]</div>

I a;ready posted the information on the bad service and the destruction of my seats, etal,. It was Bill Page Toyota in Falls Church VA. If you look at my other posts you'll see it - very unhappy experience and unlike the service I get from Miller Toyota in Manassas. My problem was that I need my Prius to commute HOV so if I have to leave it, then I am on the road over 4 hours for a commute that day - if I get there at all! So I thought I'd find a place up where I work and then everything would be cool. Not!

 

<div class='quotetop'>QUOTE(HokieHybrid @ Jun 22 2006, 09:57 PM) [snapback]275580[/snapback]</div>

Thanks -Koons was going to be my next stop - it's only a mile further than Bill Page. It's proving to be a crap shoot trying to find good Prius Techs at the Toyota dealers. When you find one, take him out to dinner and make friends!

Thanks again - nothing better than a personal endorsement.

 

<div class='quotetop'>QUOTE(DaveinOlyWA @ Jun 22 2006, 10:12 PM) [snapback]275587[/snapback]</div>

I'm going to look into when NVA got E10 to use, and if it was used last year as well. I think it was. If so, the mileage I got last two summers was excellent, well above where I am now, which is below my winter driving experience.

The variables that have been offered so far are:

Alignment - it was aligned, felt better, but felt much worse after putting on the Comfortreds the next week. This improved somewhat with the BT brace, but still is "Twitchy". Agreed - this is probably not a big contributor to mpg, but maybe some.

Oil overfill - the oil was changed by the dealer and he put in organic vs the synth that I normally run. It was filled to the top of the bars on the dipstick, so I will check the throttle body to see if this is an issue, and dump this organic mix, go back to M1.

Tire inflation - I'm running the Comfortreds at 42/40 - same as the integrities. Below that they feel very unpredictable so I'm going to leave them there.

E10 - changeover to E10 can caus a loss of energy and therefore mpg. Not sure about when NVA changes over and if this is a new thing or not. With our pollution in the DC area, I suspect this has been the case for some years, so if my previous two summers are on E10, this isn't relevant as I average in the mid 50s during the summer. will check

A/C - I checked it - I am ASE certified, and it's fine, maybe a few ounces low so I added it to bring it up to full and while it is a bit cooler, I don't detect a difference in load. With this synch motor, I doubt I would see it, except watching the pressure gauges. Nothing so far.

Computer Reflash - the same dealer did the second reflash recall for the 2004s. I have no way to know if it was done right, have to assume it was unless they only flashed a data table which COULD affect a lot of things when it comes to efficiency. Not sure Toyota will check it or back it out- we'll see.

One thing no one mentioned - is error codes. While I am not getting any idiot lights, if I go to the operational page (same one that we use to override the nav freeze while in motion), there is an error log. It's in hexadecimal, and the second page IS carrying data, (vice all zeros or all FFFFs), but I have no way to read them. ALl my error code readout devices do not marry to a hybrid test socket.

OKay - so I have some homework to do - will get back and post the results as I get them done. Thanks for all the help. If anyone has any more ideas - bring em on!

Gene