Prius Mileage 2

[msquared48]

Just had my 60000 mile service about a month ago and my mileage has dropped significantly from around 52 to 42 now. I do not think that it's all the cold weather and gas additives, but I know that plays a large part.

Last year in similar weather I was getting 47 mpg. I think I'm going to take it in and see if the adjustments were properly made during that service. I'm suspicious.

Any other thoughts or recommendations?

Mike McCann
MMC Engineering
Motto: KISS
Motivation: Don't ask

 

[MiketheEngineer]

For what it is worth - I talked to a buddy who owns one. He said the following can affect mpg by 5+/- mpg rather easily

1. Using tires not specified
2. Wrong tire inflation - presumably too low
3. Cold weather

Good luck

 

[MacGyverS2000]

Interesting... now I wonder why more cars don't use the bladder system to remove the need for an evap system. Could it be the small tank size of the hybrids compared to a conventional vehicle?

I've only ridden in a hybrid once (it was a Prius, I believe). Surprising amount of pickup, so much so that I thought it was as good as any typical $15-$20k car engine.

Dan - Owner

http://www.Hi-TecDesigns.com

 

[ivymike]

so much so that I thought it was as good as any typical $15-$20k car engine
Not bad for a car that only costs $22-$28k, eh?

 

[Compositepro]

I know little about the Prius but I'm surprised that no one has suggested that the battery may be losing its storage capacity. Batteries have a finite life and performance can change suddenly. I would guess, though, that battery capacity is something that the car's computer should be measuring.

 

[IRstuff]

I wouldn't think the storage capacity itself is necessarily an issue, since the battery energy outflow is alway made up by the charger.

That said, there are other potential issues with the batteries, i.e., do they retain the same charging efficiency over time? How well are any energy recovery systems working over time?

Given that a normal car battery has a mean life of about 3 yrs, it wouldn't surprise me at all if the charging efficiency has dropped over the time that you've owned the car, particularly since the battery in a hybrid potentially works much harder than a car battery.

TTFN

FAQ731-376

 

[GregLocock]

There's been some interesting observations on the effect of decreasing battery capacity on mpg. Turns out, not so much.

The reason is that unless you play silly biggers a new Prius keeps the battery in a 20% band for SoC, so possibly as capacity decreases it widens this band or the reduced capacity is still enough.

The calibrators are very careful to avoid putting too much into the battery, as they are well aware that the 'round trip' efficiency of that is only 60%. Much better to avoid generating that power until you need it.

Cheers

Greg Locock

I rarely exceed 1.79 x 10^12 furlongs per fortnight

 

[PEW]

My late father in law bought a Prius and had similar concerns about disappointing gas mileage. He cured the fault by buying a BMW 1 series diesel. Big improvement.

 

[GregLocock]

Gosh, did going from 40 mpg to 50 mpg really make a big difference to his lifestyle? That 1 oz of fuel per mile must be a very important one.

/Sarcasm mode off/ Small changes in fuel consumption have a tiny effect on running costs, in no way compensating for the financial (or even environmental) inefficiency involved in buying a different car. There is very little overall gain in getting a Prius driver to upgrade to a 60 mpg car, the big savings in oil are getting the 12-17 mpg SUV driver into a 35 mpg car.



Cheers

Greg Locock

I rarely exceed 1.79 x 10^12 furlongs per fortnight

 

[evelrod]

Sarcasm is a prime ingredient in life and, life is good...

I found THE fuel (automotive expense) saving device...RETIREMENT! <snicker>

My 'automotive expense' (ins., fuel, maintenance, finance chgs. and payments, etc.) has dropped from <$1400/mnth in the 1990's to $338 last month !!!!!!!!!!!

Rod

 

[patprimmer]

Rod

I found a similar tax minimisation scheme. If I don't make a taxable income I don't pay tax.

Regards
Pat
See FAQ731-376 for tips on use of eng-tips by professional engineers &

http://eng-tips.com/market.cfm

for site rules

 

[msquared48]

OK...

After 5000 miles, I'm going in for the next service today and the average mileage is just under 45 mpg, three to four mpg lower than the two previous winters, and we have had a very mild January here. Should be higher.

I'll post what they say.

Mike McCann
MMC Engineering
Motto: KISS
Motivation: Don't ask

 

[msquared48]

Well, the mechanic said that they have been receiving a lot of mileage complaints recently, and they attribute it to the gas mixture changes. Said it had nothing to do with the 60,000 mile service. Hard for me to believe.

Nevertheless, if this is so, then we are all getting cheaper gas under the guise of reduced emissions, and paying more for it in both the short and the long run. Seems to me, over the last three years, that the percentage of ethanol additive is directly related to the percentage decrease in mileage. Having to drive the same number of miles, I fail to see the emissions benefit to the environment.

Mike McCann
MMC Engineering
Motto: KISS
Motivation: Don't ask

 

[dgallup]

The corn growing agri-businesses love it. It has nothing to do with emissions.

 

[patprimmer]

I think theoretically via energy content calculations, 10% ethanol equals 3% less energy per unit of volume at the pump so if thermal efficiency remains constant you could get a 3% drop in fuel economy.

I get anecdotal evidence that refutes this, but anecdotal is not really reliable and it is quite possible that different engines and especially different FI systems respond differently to the change and I would think you could expect anything from no change to about 5% increase in fuel used for 10% ethanol.

Regards
Pat
See FAQ731-376 for tips on use of eng-tips by professional engineers &

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for site rules