Ok soooo i kno there's threads out thier about MPG but my MPG suck's *** a lot of *** about 3 week's ago i had to change my tires on my baby cuz they were really messed up my back tire's looked like they would of exploded at any minute i had 225/45 on it and i felt sometimes that the engine would struggle alot to get the car moving so i said to my self i would buy smaller's one so I ended up buying 215/45 the car now feel's more light wight and more agile but i did lose a bit of grip but that's ok to me idc also in my mind i would think i would get a littil bit more MPG then the 250 a tank i was getting......right BULLSHIT i still get 250 and sometime's less and i even took off my SSQV to try it out and put in the DV but i still get the same MPG and really i dont floor the car that much maybe when i take off to get to HWY speed's but that's all...so with a 16gallon tank im getting about 15/16 MPG WTF!!!!!! i have a CEL on but it's for my emission for start up when the engine is cold... i forgot the code number.

Do you guy's think it's that CEL that causing it or what? and wat is your MPG like?

I have a 2001 1.8T Auto/triptronic Quattro

 

CEL could cause it. My buddy had bad O2 sensor in his S4 and he said he could notice he lost MPG.

I'm no mechanic but I think with a bad O2 it could cause your car to run rich so you are wasting fuel

 

Are you actually refilling the whole 16 gallons back into the tank? I realize the FWD tank is a different size than the Quattro tank (I believe the FWD tank is larger) and even still when I'm in the red on the gas gauge my car still only takes around 12.6 gallons. Usually I will have driven about 280 miles at that point, netting almost 23 MPG.

 

I fill her up with about 16 point somthing Ive tried I have let it go all the way to like the bottom where the fuel warning beep was screaming every min or so.

 

Quick question tho where would i be able to find a cheap 02 sensor cuz ecs tuning is trying to rape me with the price.

 

Theres a website i found on the bimmerforums when i used to log on there. Its some guy who takes any factory part number o2 sensor and cross references you a alt. # that is cheaper. I dont remember but maybe someone reading this knows and can chime in. (I was a manager at autozone) and sometimes they can get universal or cross reference them.

 

When you go with a smaller tire your MPG will go down. The smaller tire will have to rotate more to cover the same distance which will cause engine RPMs to go up thus using more fuel. The 225/45 tire will do 878 revolutions per mile. The 215/45 tire will do 892 revolutions per mile. Not a huge difference but it adds up over time.

 

oh ok.