Dd I screw up my MPG?

[Homertoeclipper]

HI - I'm the owner of a 2010 Yaris Hatch, 1.5 4 sp AT, had 12,000 miles when purchased. Was getting 36-37 MPG commute driving (90% freeway). Now at 38,000 I'm getting 33-34, best.

So here's my question - I *used* to top off the tank, for the first year of fill-ups..did I ruin my vapor box because of any gas seepage into the filter assembly? That's the only change.

Oil is changed religiously. Tires kept at spec PSI, run Shell regular, avg speed fwy is @ 65-70, well maybe a bit more in some stretches.

For the record, I find it a nondescript but fine little car. Very solid with GREAT (and I do mean that) brakes.

[rayfloyd170]

You are just fine not a huge difference from your previous MPG...

Maybe you need to clean the TB & MAF sensor if not yet done and might check the spark plugs and replace if required.

I often experimented with my fuel consumption and it really depends upon the way your feet handles the accelerator (heavier foot means more fuel consumption). I have run my Yaris Sedan at >80MPH on highways and it consumes a lot of fuel comparing it when i am running at only 55-60MPH (although boring) but really huge difference it makes.

After that realization i have learned to practice not to step that much on the accelerator once it reaches 60-65MPH i try to lighten the weight of my foot and i can see drastic change in fuel economy (statistics using OBD tool proves DFCO if you dont step on gas). Try to run 55-60MPH with light foot and 40-42MPG is not impossible and i have done it several times in the past just to conclude what everybody is saying about DFCO and heavy foot. but i feel bored thats why i just averaged now at 34-36MPG and constantly running 70-75MPH.

Other than that you are good.

[Homertoeclipper]

Thanks Ray and points well taken.
My commute is pretty predictable, time and traffic flow. PLease clarify what the "TB" is...I know the MAF.

I have read lately if you get gas ito the Vapor box, you're borrowing trouble with the performance and engine efficiency. I can eek out 340 miles a week on a tank of gas, but that takes it very close down to the last "Bar" on the fuel gauge...earlier in it's life I was able to squeeze 407 miles out of the tank then the warning bar was flashing. That tells me I've maybe lost a bit of MPG.

I pretty much feather the pedal, and yes, there are a few stretches on the way home where I can open it up to 80/85.

But maybe all in all I'm bitching for little reason at all. Its nice spending under $160 a month and pumping regular at that ! First twist of the key promptly brings it to life. Solid little bugger.

My son's a tech Maybe I'll ask him to run the OBD and see if there are any codes. I know there's a vapor sensor, so if that comes up, that could be a piece.

Fill me in on what that "TB" is...
thanks

[WeeYari]

Throttle Body.

[Homertoeclipper]

Wee Yari -
Duh....(facepalm)
thanks

[mirapatec]

I have been following the scheduled maintenance with the dealership. My 2012 has had the Throttle Body Service every 30K miles. I usually run a bottle of Chevron Techron in the tank every 5K miles. My next service will be the 100K mark. My Fuelly info should be found with this post. I consistently get amazing fuel mileage driving in a similar instance to yourself.

Consider following rayfloyd170's suggestions if those points mentioned have not been serviced.

I would also suggest checking/changing the engine air filter. I believe it is recommended by Toyota to be replaced at 30K miles.