Reasons for sub-standard gas milealge

whoooooaaaaaaaaaa, slow down. how much studying have you done here? how long have you owned the car? give us some backround and hopefully, we can help!

 

What are "all the tricks listed"? Please answer the questions at http://priuschat.com/forums/gen-ii-...-answer-these-questions-esp-if-youre-new.html so we have something to go on.

 

At 65 MPH, you should get around 50 MPG, with the exception of the first 5 mins. How long is your commute?

 

Also keep in mind that manual mileage calculation is not effective for a Gen II Prius. The North American Gen II Prius has a bladder in the fuel tank, which causes variability in tank capacity. Because of this, dividing the miles driven by the fuel put in during refueling gives meaningless results for a single tank of gas. If you want to do manual mileage calculations you will need to total the miles and gas over a large number of tanks. More is better, but at somewhere around 10 tanks you start to get reasonably accurate results.

Tom

 

Why are you expecting 50 mpg or better? CR got 44 mpg (and 42 mpg on a touring) in their testing at http://web.archive.org/web/20080618...-advice/most-fuelefficient-cars-206/index.htm.

Don't assume anything about the 12 volt battery. Check the voltage.

Really? It has factory tires and it's an 07? Please get back to us on the make, model and size. Is yours a touring model? If so, they have slightly worse mileage.

Don't use auto on the HVAC system and keep the fan off when the ICE (internal combustion engine) is cold, at least during an initial city stretch. Heat on high, but fan off is ok when you're stopped or in slow traffic.

If the ICE is warmed up enough and HVAC is off, it will shutdown. If you leave the heat on, the ICE will run to provide cabin heat, wasting gas. Turn on the ICE only when the car is warmed up enough (you can't monitor this w/o ScanGauge or equivalent), on harder acceleration (where it must run anyway) or at speeds >42 mph.

 

It sounds like you are doing most of the right things. Three fill-ups is not enough for manual mileage calculation, so for the time being use the mileage figure from the MFD. It is fairly accurate for the Gen II Prius (usually about 2 MPG optimistic).

Under your driving conditions I would get 44 to 48 mpg at 70 mph. On country roads I will get 52 to 57 mpg on the flat. If I slow down to the high forties I can get mileage in the high fifties.

Short trips are mileage killers. You should do well with the 30 mile trips, but shorter than that and you will see a drop in mileage.

Tom

 

15mi on the freeway at 65mph in warm temps, little to no wind and flat road I'd expect to see 45-50mpg. Sounds like the owner is doing everything right. I'd check the 12V battery voltage - that seems to be a common issue that can cause low fuel economy.

Normally to get ~40mpg you'd have to be driving 75-80mph or lots of really short trips (less than 5 miles) or lots of aggressive city driving with the AC running.

 

+1

you seem to be doing everything well. take it back to the dealer and get their thoughts. you should be getting 50 plus. at least on the MFD and eventually on actual fill up average calculation.

 

Quick and easy test:

Find a local highway with no traffic where you can set the cruise control at 65mph for 5mi or so.

Once cruise is set at 65mph, reset the MFD. When you pull off, note the fuel economy, turn around and do the same thing in the opposite direction.

MFD should read pretty close to 50mpg.

 

There is nothing wrong with your car.

1. Reset the MFD!! !!! I cannot stress this enough.

All Prius newbies that bought used cars have this problem. The person who owned it before you basically drove it into the ground.

Also don't expect great results as youre a newbie. A month of ownership is not long.

 

macmaster05, you seem to have missed the fact that the MFD is matching his hand-calc numbers over 3 tanks.

While it is common to have 1 tank calculate 15% off from the MFD, after 3 tanks it will be within 5% or so.

 

Ohsorry I didnt catch that part. Still, reset it. Unless you already have tried that like every bad tank.

When I bought my Toyota certified prius I was getting 35mpg solid for about a week. The owner was driving it terribly. I checked the navigation history and sure enough it had been driven to oregon. A while later I realized I needed to reset the MFD and Ive gotten 52.2-54 ever since.

 

Might be your tires...I bought a Toyota Certified Used 2006 Prius and was only getting mpgs in the low 40s. A cousin here in Portland also has a 2007 used Prius and is averaging 38mpg and wondering why. I found the tires Toyota had put on were Yokohama Avid H4S's which have very high rolling resistance. After a month or so of trying to boost my mileage with all the little hypermiling tricks without success I broke down and spent the money to buy a new set of low rolling resistance Michelin Energysaver A/S tires. Immediately my mileage went up to about 55+ on the highway and about 50 on short trips and has stayed there ever since. So, I now have a set of almost new Yokohama Avid H4S tires for sale...if any Prius owner here wants to buy them the are welcome to them.

 

Soooo you're gonna make me pay for tires that get me 40 mpg? LOL. Good luck girlfriend! You would have to pay me to put these on. Later, hotness.

 

The OP (cmeek) already said he has Goodyear Fuel Max tires which are known to be better than OEM in terms of rolling resistance. Try again.

 

oh! OREGON! that's the ticket!

 

unclear about OP's tires

Agreed, provided they have the proper tires and oil, battery, and alignment checks out. I'd set the cruise control for the speed, reset the MFD, do at least a 5 min run and go back the other direction.

It's ambiguous. The OP's answer was simply "Yes". The OP may not know what the factory put on and whether those match w/what he's got.

"Goodyear Assurance Fuel Max 185/65R15" is merely the example given in my questions.

 

I am also in the Delta and drive a 2009 non Turing.

Summer and Winter I get 42 MPG, Spring and Fall, 47 MPG. Mostly driving 61 MPH on US 49.

My work takes me from Hollandale to Robinsonville, and from Water Valley to Marvell, AR So we could compare notes.


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