MPG Dropping

[NRclem]

I have an 2008 Toyota Yaris 2 Door Hatchback Manual

When I first got the car in 2009 I was getting 40mpg I kept this up or close until now. Now I'm getting 32mpg or less.

I don't drive any different. I have driven the same route everyday. Although I used to change my own oil, but the past year I've had firestone do it.

How can I figure out what's causing it or is it just because the car is getting older? I have a little over 50k miles on it.

[MadMax]

Is it happening throughout the year or only during certain times?

I ask because there's such a thing as "winter gas" which has a different (and less expensive) blend than what we get in the summer. The good news is we pay less for it (notice how gas prices have been dropping lately?), the bad news is that your mileage suffers.

More here...

http://auto.howstuffworks.com/fuel-efficiency/fuel-consumption/summer-fuel.htm

Cheers! M2

[Flipper_1938]

50,000 miles is barely broken in. Your motor should be far from dying.

1) check your air pressure. Dropping down below 30 psi kills mileage. I usually run 35 psi or so.

2) Firestone probably didn't use 5W-30 oil when they did the oil change. They used whatever they had in the bulk storeage tank (10W-40 or maybe 10W-30 ...whatever they could get the best deal on).

[jayeh]

I'm willing to go with the winter gas explanation too. I've gone from 33-36+ to barely eeking out 30mpg.

[charles nelson]

The temp here in Central MN is now -5F. I guess I am lucky...just drove home...my 2008 Yaris Auto was warmed up. No wind...got 41mpg during the last 12 miles (engine finally warmed up). Gas was 10% ethanol...winter blend.
The only time my mpg drops below 40 is when driving into a headwind.
I keep my tires at about 33-35 psi. If I don't...leaving the Yaris out in the cold...pressure can drop 3-5 psi. In the winter, I use 0-20 synthetic oil rather than the 5-30 recommended in the manual...but on the other hand I don't think that much of Japan gets as cold as Minnesota in the middle of winter.
I don't hypermile but I do watch traffic and signal lights so I don't have to stop & Go too often.

[jayeh]

I get about the same numbers when cruising, but the warmups are killing me. I don't idle at all and just go for it after a few seconds.

I live in a pretty busy rural road and go about 80-90 kph when I start out and my fuel economy tanks. It's usually about 2km of 80-90 at about 3000rpm.

Anyone else find the same?

[edmscan]

My mileage has gone from about 40 US MPG in the summer time to 32 US MPG during the winter time, so a drop is to be expected.

[NEexpat]

This is so subjective. So many variables go into mpg, driving habits and style, tire pressure, type of gas winter/summer, type of terrain you're driving on, avg. speeds, length of drives, and many more, gross weight etc.

Having my car for a couple of years now I can tell you that for me, I don't feel that my car is "warmed" up and running at it's most efficient ubtil I have driven 12-15 miles. I have noticed that my gal/hr. on the UltraGuage starts off high, obviously, rich mix. And improves after 10-15 miles. I don't just mean after the cool engine light goes out.

So far this winter I have seen my mileage drop from a combined city/hwy summer 42+ to a winter 36-37, with snows on at 35psi. 6 mpg difference, almost a 15% decrease.

[MadMax]

NExpat, for the most part the majority of those variables don't change; people usually drive the same routes using the same habits over the same terrain carrying the same amount of weight in the car. And if any do change, it's apparent to the driver.

Winter gas is the one that most people don't take into consideration as there's never an announcement or warning that it's being used.

So far this year I haven't noticed the usual decline, but I've been driving the Jeep to work more than the Yaris, and most of the driving in that car is from my teenage son who has his learner's permit so gas mileage isn't a big concern for him at this point.

Cheers! M2

[NEexpat]

MadMax, agreed about the variables. Same car same driver you rightly state the mpg would not change, save gas mix, tire pressures. Habits, routes all remaining the same.

My best guess would be the gas. I am pretty aware as to my gas mileage and I lose 15% just because of the temperature outside and the blend. Although if it has dropped to 32 in the summer that would be something else, and I don't know what that would be.

My stock answer to any of these mileage concerns is always, ( I am not a mechanic, nor profess to be any more knowledgeable on these topics than anyone else, quite to the contrary) to go for a long sustained drive and check your mileage again. This may give some insight to whether it is just the circumstances of your daily driving or something else.

[malibuguy]

mine the last 2 tanks dropped 10mpg out of effing nowhere. My last tank resulted in my WORST tank ever with a 37.3mpg...i know some of it was due to our recent snows, but damn, i can beat the HELL out of the thing any other time & still get low-mod 40s.

its not winter fuel, we started getting that earlier in the season, i usually only drop 3-4mpg from that

[nookandcrannycar]

I just filled up a couple of hours ago and I was back up over 40 at 40.9. The two tanks before that were the first under 40 in quite a while. I attribute both of the under 40 tanks (still over 39) to much more idling than normal. The additional idling came from sitting in a surprising amount (more than usual for the time of year) of traffic during Christmas shopping/errands. I finished Christmas shopping and mailing by the 22nd and the tank I just 'emptied' started use on the 24th. In milder weather, with the same driving situation, I would have turned the engine off (given the extent of the traffic) as the heater would have been off.

[thebarber]

Cold ambient temperatures mean cold fluids in the car, more effort until warmed, colder IAT = more fuel etc

Winter = shitty mileage

[edmscan]

I went from 5.5 L/100 KM to 7.3 L/100 KM and really I am not surprised in the least. It is just cause it is winter time .. and I fully expected a 20-30% drop in mileage and that's exactly what I got. I really wonder why people are so surprised when their mileage drops in the winter time.

[tooter]

I went from 5.5 L/100 KM to 7.3 L/100 KM and really I am not surprised in the least. It is just cause it is winter time .. and I fully expected a 20-30% drop in mileage and that's exactly what I got. I really wonder why people are so surprised when their mileage drops in the winter time.

I know that effect as I've kept gas mileage records on my motorcycle for almost 30,000 miles. In hot Summer weather it averages 70+ mpg, but in Winter it averages only 65.

[malibuguy]

ive been logging my mpg since ive bought the car. my winter mpg is normally 43-48mpg...even if its well below freezing, never been 37 & 40

[thebarber]

I went from 5.5 L/100 KM to 7.3 L/100 KM and really I am not surprised in the least. It is just cause it is winter time .. and I fully expected a 20-30% drop in mileage and that's exactly what I got. I really wonder why people are so surprised when their mileage drops in the winter time.

Historically the same thread pops up annually

[Kaotic Lazagna]

Winter gas, winter temps, dirty air filter, low(er) tire pressure, needs an alignment, or needs a brake adjustment/resurfacing.

[david_827]

my gas mileage drops in the winter as well, but not to that extent. I get about 33-35 MPG in the summer (ALL CITY DRIVING) and 30-33 mpg in the winter.

[WeeYari]

I love how everyone latches onto the winter gas issue, without really absorbing the details of the post.

As stated by the OP, who appears to be another 1 post wonder who hasn't come back:

When I first got the car in 2009 I was getting 40mpg I kept this up or close until now. Now I'm getting 32mpg or less.

He has gone through 3 winter cycles without observing a notable drop in f/e. Like myself, who has noted a drop (8%) unrelated to winter in the past 12 months, the OP is now questioning his observations. Kaotic at least has extended possible causes to things other than winter gas.

[why?]

ive been logging my mpg since ive bought the car. my winter mpg is normally 43-48mpg...even if its well below freezing, never been 37 & 40

for you, i would see what has changed in the past year. And then recheck everything it could be, like tire pressure, fluids are too dirty, etc.

actually that would work for everyone too.

my mileage has dropped dramatically, but for me it was idling a ton. i don't really care because it will go back up when i drive, and i generally only fill up twice a month.