2005 Prius with Very Poor MPG

Any other vehicle on the market could have developed a problem even worse than reduced gas mileage. You're lucky you didn't get one of those because then you would be at 20mpg!

Seriously. Stop hating and get the car fixed. It is obviously not working within spec.

 

All vehicles suffer in the winter. Seasonal efficiency drops often go unnoticed. Having a screen available raises awareness profoundly.

Do you ever warm-up prior to driving away? (that's extremely wasteful) Have you checked your tire pressure? (that naturally drops, cold temps make it worse) Do you drive nothing but short trips? (the penalty is obvious on the consumption screen) Would you be willing to take 20 minutes and spend $2 to block your grille? (that works great for heat retention) Is this temporary MPG drop really that bad? (much higher will return in a few months)

Just go for a long drive. The first 10 minutes are always painful in comparison to what follows. MPG goes way up once the engine and emissions-system is warm. Nothing is wrong if you see numbers above 40 at a steady cruise then.
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Hi jdog...,

Do not worry, come late spring you will be gettin 50+ mpg again. Yea, you probably wasted your money on the diagnosis.

Look around on the website for the sticky regarding poor mileage, and fill out the questionaire, and post it back on here.

Check your tires, and run them at 42/40 psi. These need to be set first thing, before any driving, in the morning, on a cold day.

You are going to need to grill block. You can start in the weather we are having now by blocking the top grill slots right away. Do NOT use styrofoam. Do a search on Grill Blocking on here and you will find lots and lots and lots of information.

In 5 degree weather, getting much better than 45 mpg is almost impossible on secondary road travel. On the highway, it depends on how sunny things are (to keep the tires warm).

F8L is wrong. It could very well be just fine. If your doing short trips. Or if the temps are below 10 F where you are, then, yea low 40s is typical. And this is from somebody who has done 70 mpg tanks in 80 F weather in Chicagoland suburban traffic.

You are falling into the same apples compared to oranges comparison many people do. 30 mpg is what you getting in 5 degree F , for short trips. You can tell that because your Prius has a mileage gauge. You really do not know that these other cars are not getting 15 mpg in similar conditions. My 2000 SL2 got 28 mpg in the summer, but 20 mpg on a tank average basis in the 5 F weather. If I drover the SL2 for 10 minutes at a time, then parked it and let it cool, well it would be getting allot worse. I do not know how much worse, because the SL2 does not have a gauge. I have to wait till I gassed it up to find out, but by then, I would have had long trips during the same tank, and the mileage is up to 20 , in 5 F weather.

 

I have an 06' and drop to 47+ during the winter, I'm at 50.1 right now, something is fishy
The usuals
cycle the emergency brake on and off, cable might be sticky
clean the cabin air filter
Tires at 42-40
Oil 2/3rd's up the dipstick
Put in an optima yellow top battery with fit kit



I suspect you have a spark plug mis-firing

 

Please follow john1701a suggestions.

There's a reason why I posted http://priuschat.com/forums/gen-ii-...-answer-these-questions-esp-if-youre-new.html. We know nothing about the OP's trip lengths or drives.

If there were misfiring, it should trigger a check engine light/MIL.

 

Just my opinion, but goodyear tires are junk. I used to buy nothing but them, but after the last set, I will never buy goodyear again. I would suspect the tires, IF that is the only change that has been made. I agree other factors need to be considered like some of the other comments have indicated. But I would point to the tires being the problem.

I am not sure how you can confirm it other than possibly swapping the tires (correct size, rims and all) with another person just as a test. It would be a lot of trouble for sure, but it might be the cheapest way to tell instead of having the car diagnosed at the dealer. Just a thought...

 

Yes.

Tire pressures should be checked at least monthly. Always check tires "cold" (that is, when they have not been driven more than one mile in the previous hour). Checking them hot will give an inaccurate too-high reading.

 

OP - I bought similar tires just before Thanksgiving - I bought the Viva Assurance Fuel Maxes which are the Walmart exclusives. I found that my mileage trended up a touch - I also found that they handle very well in rain and snow - so at least my experience with similar tires has been very positive.

So - I'd just tell you not to worry too much - the cold will take a heck of a hit on mileage.

 

1) What brand and model of the tire are you using now? Is it 185/65/15 in size?
2) Check if your Coolant Heat System pump is working. It stores hot coolant in a vacuum bottle to release it during the cold startup. If it is not functioning, it will hurt your MPG especially during winter.

 

We can only speculate until jdogg answers cwerdna's list of questions.

Jdogg's experience is certainly possible for a properly running Prius. My summer mileage is in the 50's, now I'm struggling (as usual) to keep it above 40 mpg, and that's with grill blocking, an engine-block heater and using hypermiling techniques, including monitoring engine temperature with the ScanGauge and using the heater only enough to keep the windshield clear. Before I did all that I would also have tanks in the mid 30's mpg. I'm maybe 20 miles south of Wisconsin, so the weather is similar.

In my experience, commute distance and air temperature make a much bigger difference than tire pressure (assuming you're not grossly under-inflated). Generally your commute is fixed, so to improve your mileage one easy step is raising the tire pressure, but we shouldn't get the impression that's the biggest factor. I have a commute of 3 miles, that's my killer, especially on days like today (-5'F this morning, or -20'C for our international friends) and I need to run the defroster to safely drive.

I recently replaced my tires too, but haven't noticed any hit. I used the Michelin Energy Saver A/S. A bit expensive, but had good characteristics - quiet, LRR, better braking distance than the OEM tires. I've heard some tires take awhile to break in and provide better mileage.