what should i do to improve it? i filled up 50 dollars of gas, and by the time i got to E the odometer was at 280 miles. i got the car a month ago, changed spark plugs, air / oil filter, oil, rotors, brake pads, front bearings. i drive almost completely on the highway, and i ALWAYS use cruise control. no check engine light or anything

 

i have the same vehicle except mine is the EX model, ive had it for about a week put in a k&n airfilter didnt seem to make much of a difference i havent tried to measure the mpgs but im possitive is around what you're getting

 

Usually when MPG is low like that it has to do with the Oxygen Sensor/s. Even if the MIL isn't on it may have a stored code.

 

curtie94, that reminds me, mine has the check engine light on i took it to see what it was and as you mention it's one of the Oxygen Sensors that has to be replaced

 

Ya a bad o2 sensor can cause really bad MPG and in some cases idle surge and other idle problems. You should change it. It is a DIY job if you want to but you usually need to heat it to get it out. I usually use a propane torch because its what I have.

 

Be careful guys before you throw parts at it.

The code tells you what is wrong in that circuit, not the actual part being defect. One time at my shop, a Corolla came in with a Bank1 sensor2 code, they replaced it. 2 days later the guy came back. Found out it wasn't the rear 02 sensor, it was actually Bank1 Sensor1 that was defect because sensor 1 couldn't be read by the ECU and it was throwing sensor2 off which sets the light off......

So diagnosis on this stuff is a must!

 

$50.00 worth of gas = how many gallons?

 

The biggest mpg reducer is when EGR valve and ports are clogged as the car is dumping fuel thinking that it's going to be burned efficiently but it's not because the egr gasses aren't entering the system and are being blocked. Normally when egr ports are clogged u can actually smell fuel while driving.

The second is O2 sensor.

The third is fuel filter.

 

Unbelievable! 40 dollars of gas (12 gallons) got me 200 miles. Average of 18 mpg. I dont get how a 4 cyl could be so bad
Ive never smelled gas while driving

 

Are your plugs gapped correctly and are they OEM equivalent?

 

I would check the timing first, even if it is throwing codes, I would check the timing first.

If you don't have one, borrow one, or see if you can borrow it at autozone.

 

One other biggy that no one has mentioned yet is if your valve lash is out of adjustment it will throw your mileage off.