Actual vs indicated mileage: Prius not delivering ?

I don't think it has much to do with possible accidental ignition due to the electrical thing. If it did, they would have to ban all other vehicle movement while someone was fuelling up. I think it has more to do with certain valves being open/closed when in "ready" that could lead to contaminating the charcoal canister system?

 

Thanks Larry.... That makes good sense... No more Ready Mode on fill-ups for me. Wes

 

On my first Prius ('04) I cut away the foam seal at the top of the filler neck. No more overfill or bladder bursting possible, no gas burping back, etc., etc. The California air pollution people probably consider that illegal, but I live in Florida. Have had no filling problems on my '07 so far, except that one pump that I normally don't use was too sensitive and shut off prematurely. Even that wouldn't happen with the seal cut away, since no pressure can build up in the bladder and the pump will shut off when liquid backs up into the nozzle - what the shutoff mechanism was designed for, not the high vapor pressure that sometimes occurs with the nozzle seal intact.

 

I know this has been discussed frequently, but I'd like to add my voice to those who feel that the computed (manually) vs. indicated (on the MFD) mileage are out of whack.

I've driven about 5.5K on my late '07 Prius (package #5), from last August (warm, but not not, here in Western Washington) through March (somewhat colder, but not real cold).

I've manually calculated the mileage for EACH of my tanks, and WITHOUT EXCEPTION, the manual calculation has come out below the MFD indicated mileage. I recognize the variation in filling, bladder inflation, etc., but it shouldn't always deviate in the same direction! The difference has ranged from small (about 1 mpg) to larger (about 5 mpg). Something just doesn't seem right. Can the thing have its calibration checked?

 

Have you checked the calibration of the gas pumps? They are allowed a certain amount of error, depending on the jurisdiction, and guess what, they almost always error on the short side.

Tom

 

Sure, but doesn't it seem unlikely that ALL of the stations I use would have the same issue?

 

Not when it makes money for them.

Tom

 

Most (85%) of my 52 fillups have my calculated mileage come out below the MFD mileage. I've never been able to explain why it hasn't evened out. But I put my faith in the MFD as it is supposedly quite accurate.

 

After a year of Prius ownership (32,000KMs , 20,000 miles) the economy I get varies from 4.5 L/100KM (52 mpg) to 5 L/100KM (47mpg). There appear to be two main factors for city driving economy: the outside temperature and distance travelled per trip. The shorter the trip the worse the economy. The cooler the temperature, below 15 degrees C, or the hotter above 30 degrees C the worse the economy.

From what I can find out, the engine needs to get to an optimum temperature for best fuel economy - which takes a certain distance. This distance is longer when it is cold outside. When it is hot, a certain proportion of energy goes into running the aircon.

Recently, with the temperature around 20 degrees C and an average trip length of 25KM we have been getting 4.5L/100KM.

Cheers,

Michael