Cold Weather MPG

yea, I found that just a little bit ago.

out of sheer curiosity - what made you go to 80, and is it worth it?

 

I'm trying to find out where the mpg benefits level off from adding more psi. As for whether or not it's worth it, I would refer you to my mpg banner in my signature and take special note of the one month figure. That came as a result of one tank at 101 mpg and another at 99 mpg.

 

Larry,

When you are signifcantly higher than max psi (which 80 psi would qualify...handily), are you seeing even wear?

I've read in many places from people who are filling to the max PSI that they are either seeing even wear or still seeing more wear at the edges. The guy at Costco gave pause when I asked him to fill my tires to max PSI (not recommended PSI), and he said that I would see uneven wear (centers wearing out first). I repeated what I wanted and it was done. (I had read many threads about max PSI, so I wasn't worried).

 

The wear seems to be even across the tire as near as I can see.

 

The reports I have seen convinced me that high pressure in tires makes them wear longer and more evenly.

 

Ah -- I see how you do it now. Your car floats = less fuel used!

 

You have no other mods?

 

I still haven't blocked my grill and my MPG went from 53-56 to 46-47 since the temperature dropped to the 30's. Ouch!

I guess I know what I'm doing this weekend haha. I also haven't inflated my tires since September. I checked them a few weeks ago and they were still at 40/38 somehow.

 

I got the grill blocking going again this year, but it still hasn't stopped the drop. One month ago I was still playing with 60 MPGs. Today (with a high of 23 F) I'm feeling fortunate to be above 45 MPG!

There is a REAL reason my lifetime mileage is only in the lower 50s. I am in the high 50s for most of the year and in the mid-40s for a about three or four months.

I have not yet installed an EBH, and I am certain that is what will allow me to boost my winter MPGs more than anything else.

 

Its mostly the difference in fuel formulation that affects your mileage, not the temperature. You'll generate more power at low temps due to a denser air charge (this is good), but the fuel is oxygenated in the winter. If you fuel from the summer stored somewhere and put it in your tank, you'll actually watch the mileage increase. Your block heater probably helps because it keeps your motor from going into cold start enrichment. Modern cars will run rich when cold to help light the cats off earlier and it murders fuel economy.

 

I drop from 42-45 down to the mid 30's every winter. sucks, but I'm resigned to it.

 

No, it is not. The problem is in keeping the engine and passengers warm. The engine has to run more in cold weather for purely thermal reasons and that hurts fuel efficiency.

Doubt me? Then ask yourself this: why is the mileage lower on cold days than warm days for the same tank of gas? (Hint. It is not due to reformulation.)

 

I have not yet installed an EBH, and I am certain that is what will allow me to boost my winter MPGs more than anything else.[/quote]



Please tell me what a "EBH" is???

 

engine block heater
heatsup the engine before driving.

 

Lots of stuff in here about blocking grilles, but what about heating the battery under the seats. I notice that on long trips, as the passenger compartment warms up, MPG goes up. I'm considering taking the back seat out, adding a plug in heater, insulation under the battery pack or foaming the bottom of the car...than kind of thing. Anybody try any of those things?

 

the mpg's go up because you ICe and parts behind it are heated up

 

An EBH is an Engine Block Heater. You can purchase one in the PriusChat store. There are threads on here that will tell you how to install the EBH once you get one, or you can bring it to your mechanic to install.

http://priuschat.com/forums/prius-m...ine-block-heater-yourself-guide-may-help.html

Blocking the grill helps the engine (ICE) retain heat once it is fully warmed up. The warmer your engine, the less it will be inclined to start to keep itself that way (hence, better MPG during the summer as opposed to winter). Keeping the traction battery warm is not a good idea, and will decrease the life of your battery. The traction battery needs to be cooled, and the Prius has a system of vents that do exactly that.

 

Looks like I found the Prius' threshold for temperatures it will absolutely not tolerate. Anything under 40 = mpg go bye bye.

This is my MPG from everyday being raining and in the low to high 30's (besides one day) and the other is a full day of driving, 20% small roads 80% highway in the 40's.

 

For a variety of ideas this is a dumb idea. Battery CAPACITY goes down with lower temperature, but battery LIFE goes up with lower temps. The reality the thermal mass of the battery takes a while to warm up, but by the time the cabin is warm, the battery goes through a few charge cycles, the battery will be warm. It is a solution in search of a problem, unless you live in Winnipeg or Whitehorse maybe.

Icarus

 

Mine has done this consistently and I've noticed a difference in almost identical drives in different directions. One drive is pretty much at the same altitude as my home while the other is down the mountain: i get much better mileage on the former. I think this is related to air resistance, i.e. the air is denser at the lower altitude.
A few folks on this forum recommend the heater but I just wonder how much this will help. I also note the recommendation about blocking the grill but...not sure what ambient temperature requires this and when this could lead to problems.