Bad MPG

[Ossy305]

Well I bought my Yaris Sedan Auto with 112k from the original owner and I seem to not get over 250-260 miles per tank. I don't drive crazy or rev the car high. I mostly do city living here in Miami FL. Mpg hasn't changed since I added the yakima roof rack and the 17" XXR. My ac is always on. I did replace the spark plugs just for maintenance with NGK ones. The air intake filter is clean... Any suggestions???

[WeeYari]

Tough one as you have so many variables.

Stop and go driving, A/C on, and big wheels are an economy killer. Also, stating miles per tank is highly subjective as we have no way of knowing at what point you are topping up the tank. Do you have a gallon left in there at the time? Two gallons? Who knows.

What you need to do is a proper mpg calculation. Top up tank to one click of the pump. Take your odo reading. Do your driving and top up again, preferably at the same station/pump to one click. Record the actual number of miles you've driven and calculate.

Also, get the thing out onto the highway and give it a good cruise. What you would want to do is the same exercise with highway driving if possible. Top up, record, get out on the open road. Come back, top up, and calculate.

Maintenance things to check/perform:
- clean the MAF
- check for brakes dragging
- inspect tires for uneven wear, indicating alignment issues

[why?]

What WeeYari said. Also see if any regular maintenance was done on the car. Transmission fluid can kill gas mileage, and so can a ton of other things.

But to be honest, with you conditions and all city driving your gas mileage is not that bad. The most I've seen anyone report in a Yaris with all city driving was 32 mpg. You are not that far off.

[Ossy305]

Wheels have been on for only 1000 miles. Brand new Hankook V12s. I did clean the maf about 1000 miles ago too. How do I check for brake drag?

[Ossy305]

So I really shouldn't worry that much about it?

[WeeYari]

Originally Posted by Ossy305

So I really shouldn't worry that much about it?

Do some actual mpg calculations. Doing a highway run will no doubt really surprise you. The difference with this engine between highway and city economy is often huge. Go out and get us some definitive numbers that we can digest for you.

[WeeYari]

One other thing. You've not told us what size your Hankooks are. Chances are with aftermarket wheels, you are not running a wheel/tire combination that is the same diameter as OEM spec.

Use the information found here to see what your diameter is vs OEM. http://www.yarisworld.com/forums/showthread.php?t=5021

This does effect the speedo and odo, so you're potentially not driving the distances you think you are.

As why? has stated, you are not necessarily all the bad. Especially when you consider that you are running the trifecta of mileage killers.

[CTScott]

Tire width and compound does make a huge difference I lose about 5 MPG with my 205 width Nitto Neogens versus my original OEM 185 width Goodyear Eagle LS (and those are both on the same rims).

[IllusionX]

I would say that 250mi is about right, giving that AC is always on and running on 17'' tires...