Gas mileage guage screwed up?

[teikyo30]

My gas mileage gauge keeps changing readings. I have been driving it the same for a while: steady as she goes. I don't have a job right now, so I can't afford to tear around and waste gas.

Normally it shows my average at around 19 mpg. Yesterday, with no change in driving, it dropped to 15.6 If I wanted Jeep fuel economy I would have gotten a Jeep or the FJ Cruiser. What's going on with my car? I change the oil pretty regularly, I change the air filter almost every time I do the oil (I look at it first to see if I need to), my tires are at the right pressure, and I use 93 octane gas. What's going on?

[oguitar]

Don't go into boost if you want to save gas. That is if your car is in perfect running order. Hard to guess whats wrong with your car over the internet.

How old is the 02 sensor? Got any mods? Need more info.

[teikyo30]

The car is stock, no mods. It hasn't had a tune up, ever, but a mechanic I took it to said a tune up is a rip off if there's nothing wrong with it and Subaru has had the car a few times and confirmed it's running in perfect condition.

How do i avoid boosting?

[EJ257]

What mileage do you get when you calculate it manually?

How do i avoid boosting?

With a light right foot.

[teikyo30]

What mileage do you get when you calculate it manually?



With a light right foot.

Umm, I don't calculate it manually. I go by whatever the computer says and add gas as needed.

[EJ257]

Umm, I don't calculate it manually. I go by whatever the computer says and add gas as needed.

Mileage computers are often times off; try calculating mileage manually. When you fill up, reset your trip odometer. Next time you fill up, divide mileage / gallons.