Gas mileage dropped bad

Spec V 2 fast · Nov 29th, 2005, 05:41 PM

I filled up my gas tank with premium as always and I didnt bother to look at what MPG i was getting. When the temperature droped like 30 degrees overnight here in VA I went out that morning and cut the car on. it turned over no problem and i bothered to look at the mpg display and it had dropped from 24.2 to 17.4.

Im assuming that it may be a bad tank of gas but im not sure if it could be something else. everytime i get in my car now i look at the mpg reader and it has moved all over the range from 16.5 to 19.1 and almost 20, but not near my normal 24.2.

I do let the car warm up and after a while of driving it still doesnt go back to normal, and yes I properly broke her in.

I have a 2005 Spec V with 8k miles on it and only a Nismo cold air intake. any ideas on what can cause such a drastic drop in mileage. Im gonna go through this tank and get gas from a different place and see if it goes back to normal if not tho im going to take it to the dealership see what could be possible.

Any ideas or comments would be GREAT

xbrandonx · Nov 29th, 2005, 06:26 PM

you can't use that to accuratly check your MPG.

The only way to do it is to fill the car up and set the trip odo. On your next fill up divide the miles on the trip ODO by how many gallons you put in.

neogeon · Nov 30th, 2005, 05:25 PM

^ He's right, you can't go by instantaneous mpg b/c it changes all the time depending on acceleration, etc. Also, colder weather causes fluids to compress and would make it seem like your car was using more gas. I don't think the difference should be that terribly drastic, but that could have a small influence on it.

xbrandonx · Nov 30th, 2005, 05:57 PM

to prove the point when you hit a downhill slope, give it a bit of gas and reset the trip odo when you let out and look at the 99.9 MPG goodness.