lower MPGs in winter or problem? PLEASE HELP :)

Well first off, I would look for a Toyota Dealer. I really would not want to drive my Prius into a Honda Shop, unless they were the last place earth!

As far as the MPG hit, winter will give you quite a hit, when is the last time you visited a Dealer for service? What is the charge on the 12 volt battey? When they start to die, MPG takes a hit, as well as other anomalies. It may be that you are having two problems at once, COLD & Battery problems!

 

You will get lower mileage in the winter, esp. in your area when it gets really cold. This isn't hybrid nor Prius specific.

How many "miles per tank" is a very inaccurate means of measurement. We have no idea how many gallons were actually consumed. Also, since you have a 2nd gen, it has a bladder tank so its capacity goes down in colder temperatures.

Please manually calculate (and record) your mileage and also report the MFD values after each tank. Also answer questions at http://priuschat.com/forums/gen-ii-...-answer-these-questions-esp-if-youre-new.html if you want mileage help.

 

Welcome. Situation normal. No cause for alarm.

If you haven't checked, your tire pressure is probably low. Increase to max sidewall pressure.

Block the grill. Tony started the definitive thread.

You can check the 12v battery's voltage by entering Maintenance Mode on the MFD.

A popcorn popper has nothing on my 2010 after a cold soak. Turn up the volume.

 

It is doubtful that you have a major problem. All of the suggestions above are good. I have come to realize that to consistently achieve 50 mpg or better, everything has to be just about right: tire pressure, head wind, traffic, on-board load, dry pavement, and etc. Remember, winter blend gasoline lowers fuel efficiency as well, cold weather means the ICE runs more to maintain cabin and pollution control heat, and pushing the tires through standing water and snow increases the rolling resistence. Wait until is warms, and your fuel efficiency will be back up.

Every vehicle contends with the same issues, and their fuel efficiency drops as well. It is just that we Prius owners are very mileage concious. Heck, I rarely even check the mileage on my other car, but I document every mile, every gallon on my Prius.

 

Hi Casi...,

The 2nd Gen Prius, like your car, has a rubber bladder in the gas tank, which reduces Volatile Organic Emissions (gases leaking out of the tank). The rubber shrinks when it gets cold, or maybe it does not stretch as much, whichever, the capacity of the tank is much less in cold weather.

So, your mileage is not reducing by the amout of your tank refill distance would indicate. Because, the amount of gas you can get into the tank has shrunk as well.

So, I do not think you have a problem. But, just to be safe, do a search on the 12 V battery and Mileage. You will find a proceedure for checking the battery voltage. If its greater than 12.0 V after resting overnight, your good to go. If its below, its probably good to get it replaced - and that will improve the mileage.

Another thing you could have done is getting the MAF (Mass Airflow sensor) cleaned. At 78 K doing this wont hurt, and very well may help.

Keep after the tire pressure as the temps go down. Tire pressure falls 1 PSI per 10 degree F. So, if you set your tires to 42/40 psi at 50 F, at 10 F, they will be down to 38/36 PSI, which will be poor for mileage, and wear on the edges worse as well.

 

Mileage cut in half is a bit much.

I tend to get about low 50 MPG in the summer and mid 40 MPG in the winter.

 

As others have have mentioned you have at least two things going on.

I'd the fuel tank bladder- it is stiffer in the winter so you can not get as much gas into in when cold. I believe that the listed capacity is 11.9 gallons- so with the bladder you likely have that much in summer, but could have more like 10 in winter

The second thing is the mpg hit in winter- the cold just saps mpg's. I do a mostly short trips during the week- I average about 45 mpg in summer but only 35 in winter.

I also find the gas gauge to be less than reliable - my last fill up was just after the gauge went to 2 pips but I put in less than 7 gallons to fill it. Are your fillings all about the same number of gallons?

All of these may be factoring into your mileage per tank. Better bet is to look at mpg - that will give you a better idea of what ig going on.

 

I imagine it depends greatly on your average trip length. If you have a 20 minute commute the winter will increase the percent of time you have a cold engine more than if you have a 40 minute commute.

 

My boyfriend knows a lot more about cars than I do and said that a car will usually drop 5 or 10 mpg in the winter. To date, mine has only dropped one mpg, but I live in the desert.

I would take the car to a dealership for the rattling you're hearing, but the mpg seems normal.

 

Check out some of the threads re blocking the grill area. Car warms up much faster. Warm up time is a killer with the Prius as well as short hops. H

 

I've got an interesting test of that coming up.

Here in MA, it was mild for the first part of my last tank, and my MPG went back up from 52-54 (tanks/MFD) at 25-30 OAT to what I was getting in September (i.e. 60-62), when it was around 60-70 degrees.

Then we had a cold front and are now back to the deep freeze. Being unwilling to see this tank.....well, tank back down to the low '50s, I finally blocked my grille today, using the excellent instructions provided by PC. It was easy!!

I'm at 62.5 MPG right now, with 325 mi and 2 pips left, and I'll probably fill up again after tomorrows commute (52 mi or so).

It will be interesting to see what happens........

 

Interesting.

Never saw a post by a Klein bottle before.............