Recently I noticed that after I drove only 100 miles that half of my gas tank was already empty, the car is running a little sluggish and when I am driving and put the car in neutral I notice that the dash lights dim a little and when I put it in gear light up again. At first I thought it was a bad coil pack making me run rich but then again my car doesnt shake or misfire. I recently changed the spark plugs about 2000 miles ago with denso iriduims so thats not the problem. Any Ideas?

 

any CELs? also im pretty sure it has to do primarily with your running rich issue. was the car running rich before you put the plugs in? any issues with the maf? maybe your o2 sensors? there are many variables. we need a bit more information.

 

Calculate your true MPG on 1 full tank, then report back.

 

11.4 Mpg...im getting Hummer MpG without the cool hummer look! The car was not running rich before, I got 300 miles to the gallon before now im lucky to see 200 no CEL either

 

That’s a little high.

 

Is that a new Hybrid or something ? like a tesla roadster?

 

uhhh no, that's a lot high. Could be O2 sensors, coils, get the codes and go from there.