ok 75% of my driving is hwy at at least 55mph. when i first got my car about 4 months ago i would get 27 mpg or so. now i am getting 21. the only thing i can think of is maybe when i added my new head unit that when i disconnected the battery something got reset. does anyone know what might be the problem?

any help is appreciated!!

 

Summer gas vs winter gas probably plays a role too. I lost close to 5mpg/tank

 

ok thanks for the response i didnt even think about the diff gas in winter.

 

wouldnt summer gas get less per tank?
hot=gas expands which = less gas per tank
cold=contracts which = more gas per tnak

 

you tell me. i always heard about worse gas mileage in winter and a diff gas used in winter.

 

Any more likely since they are forcing all our gas in Missouri to be a Ethanol blend. All gas sold in MO is now minimum 10% Ethanol.

Ethanol=poorer gas mileage.

The part that blows the most is that they changed over here (in Columbia) 4 months ago and kept the price high although it was supposed to go down...

Our government at work...

 

and since its colder the air would be cooler which would make the engine run better. but im not too sure on that

 

hey mach that prob is the some of the problem.

 

6mpg is a big drop even for winter blend

 

Winter blend + ethanol + cold air being more dense = more wind resistance, + possibly lower tire pressures due to the cold?

 

I let my car idle more in the winter to defog/defrost the windows and warm up the interior. All that idling really kills my average mpg (about 2-3 mpg less) according to the message center readout.

 

yea im averaging 16mpg right now.... ouch ouch ouch

winter sucks!!!

all in town driving

 

I've also read that the fuilds in the transmission, rear end, and the engine oil take longer to get up to temperature in cold weather, so they remain thicker longer which increases friction and contributes to a decline in fuel economy.

 

yup winter definetly = lower gas mileage.

The computer compensates for higher air density by adding more fuel.

Actually if you drive at higher altitudes (on relativly level road), you'll get better gas mileage.