Rep Power: 0

Hi,
I'm new to this so bear with me! I just moved to Missouri from Colorado, and my 2006 Civic LX is driving a little sluggishly and its gas mileage has been terrible. My car usually gets 30 MPG in the city and 40 on the highway, but lately I'm getting 26 MPG at best, including highway driving.
In the past few days, I've also noticed it takes a bit longer to turn over when I turn the key -- the starter works, but it revs for a couple seconds before ignition.

I am wondering if this is because of the altitude change, the increase in atmospheric moisture, or something worse -- like a battery problem, spark plugs or something like that. Any ideas? I am taking it in for a (slightly overdue) oil change this week and would like to be a little prepared before I talk to a new mechanic!

My car has about 48,000 miles and has had routine maintenance, but no major work (original belts, battery, etc.)
Thanks a million!

 
Rep Power: 812

im sure it is, car uses more gas at low elevation where theres more oxygen. if its humid, it may be affecting how the car runs. at high altitude there alot less oxygen so less fuel is injected. just keep driving the car for few hundred miles or so and eventually the ecu will learn the new conditions and adust so it wont be as bad. my car was in shock too after moving from sea level to 5k feet.

 
Rep Power: 0

id say give it some time and see if the car adjusts

 
Rep Power: 245

Or, do the idle re-learn procedure. That should take care of any issues with elevation etc.