Getting horrible fuel economy

I'd more or less put the loss in MPG due to cold weather, I live in maryland and my mileage has dropped from a high average of 60 to 65 mpgs in the summer/fall to now only average 48 to 53 in the winter with no change in routes or driving habits. Can try to do the grill blocking to improve mileage(Which I haven't done myself yet)

 

The OP talked about running out of fuel faster in the cold. I think it's due to the contracted bladder in the Prius that can hold less fuel.

 

Really, Mr. 1 post?

/not buying it

 

I buy it. the guy's not obsessed with this stuff. He's just annoyed now and now that it's a problem and his dealer isn't helpful, he came here for information. totally logical.

 

It's both. In cold weather the tank holds less usable fuel, and mileage is lower. It's a double whammy.

Tom

 

Understand.

This winter I've installed an EBH as well as blocked the grill. My tank avg has gone up from 46 to 50mpg in spite of the weather. Nevertheless, the fuel gauge goes down to 2 pips by about 350 miles now vs. 400 or more in the summer...

 

Butch, I was asking pepper04 those questions.

My guess is pepper's commutes are very short. Thus he never reaches engine operating temps or stage 4.

 

Thanks for the replies and sorry for the delay in my own reply. My trips are usually 4-10 miles, but the mileage doesn't seem to improve much with longer trips of 10-20 miles, but most of my driving is in the city. I live in Boston and it has been a very cold and snowy winter, but I didn't notice a drop the last two winters. The toyota dealership put in a nitrogen fill on the tires, changed the air filter and I've had a recent oil change. I do not have a grill block but will look into it. I do not think it has to do with the bladder in the gas tank because I still fill up about 9-10 gallons each time and get about 200 miles per that tank. Maybe this car just was not meant to be driven in the city?

 

city driving is hard because of all the stops and starts, getting up to speed is where you use up the most gas and when you have to stop soon thereafter you lose your efficiency. It seems to me that the cold is very significant in dropping mileage AND the short trips are even worse. Finally, the snow also seems to be a major drag as driving over snow and ice reduces your ability to coast or glide requiring constant use of the ICE and reducing mileage back to a more conventional vehicle.

In the winter, I've become content in the low 30's, and happy when my tanks exceed 35 mpg. I still hate the fact that 200 miles seems normal for a tank, but am pleased to have 240 on my current tank and still 2 pips up. I'd like to get 300 at least per tank.

 

If you can stand to run the cabin heater at a lower temperature that will help. Don't warm up the car before driving. Check the tire pressures at least monthly, or whenever the average outdoors temp changes by about 20'F or more. And don't pay money for a nitrogen fill; it has negligible benefit.

 

There are lots of threads about what to look for so I'm not going to repeat them.

For mileage this bad I assume the ICE runs constantly? I have a hard time imagining how the mileage could be that bad on the longer runs, even with the blower on max with defrost on and highest temp setting (which would probably keep the ICE on continuously.) Something sounds seriously askew to me.

 

It could be a dud 12V battery. There are reports of big drops in fuel economy as the car wastes power trying to charge a battery that won't take a charge any more. Any unexplained failures to switch on? Dimming of idiot lights if you put the car IG-ON rather than READY? If all your driving's short distances, the 12V may not get a chance to charge properly.

There's a back door into a diagnostics mode on the display, which has an option to show the voltages. See this page for how to get to this screen.

The numbers on my 12V battery seem weak and the car's only a year old! I suspect it wasn't cared for properly between arriving at the dealer and being used as a demonstrator.

 

The cold definately hurts mileage. I averaged 51-52 all summer. Since we've only had 30 hours above 32 in the last month or so, I'm down to around 44. Still, much better than anything else I've ever had. Like someone else said, we really notice the hit in a prius.
Still love mine, and wouldn't want anything else.