Here's my story.
Had the car a year now (almost to the day), stock, have put 5000 miles on it, all the fluids blah blah blah.Suddenly I'm getting 30-40% better mileage.No changes in driving. No changes. Searched the crap outta this.
I'm wondering if it's something the ecu is pulling off, but honestly that's simply a guess. Obviously I'm not complaining, however I am confused and looking for info.
Thanks for any input.
It's a IX/MR. 28k miles on it.

 

My 03 8 has about 75k miles on it, this past week i've gotten 28mpg highway, i was astonished, driving from mid missouri to chicago i only used a 1 1/3 tanks

 

Did the weather get better (warmer)? In cold/cool weather I get 17-19mpg on warm/hot weather I get 19-22mpg.

Also maybe the gas station switched from winter blend to summer blend and its giving you positive results?

 

Switched gas stations? Maybe to one that isn't using an ethanol blend?

 

No change in fuel stations. I live in Vancouver BC and use Chevron 94.
Weather here is all over the map!

 

Most likely gas blend + weather change.

 

Yea most likely your gas station stopped using that 10-15% ethanol garbage.

 

Can weather have that much of an effect?

 

If your egr line popped off and you put it back, this could cause this.

 

Nope. Nothing popped off or anything like that. It has also been 600 miles of awesome so far. Weird.

 

Nope. Nothing popped off or anything like that. It has also been 600 miles of awesome so far. Weird.

 

Lulz.

You DO know that non-oxygenated, non-blended fuel knocks like crazy in boosted motors, right?

Never mind that all standard fuels are required to be mixed to 10% Ethanol content by federal mandate. If it's not blended, it's marked very clearly as such and must be sold in conjunction with a fuel that is.

 

In canada chevron 94oct is ethanol free. Also my monster car payments have made it impossible for me to install a wideband so knock sum is a mystery.

 

Widebands don't show knock.

 

Fuel changes from winter blend to summer blend in April I believe.

Check your fluid levels (trans, front diff, rear diff, oil).