the other day, i drove about 60 miles on the highway(70mph), and about 2 in town. i don't think i ever went full throttle(which is hard for me not to do), because i wanted to see what highway gas mileage was. To do this, i filled up before i left, and then filled up right when i got to town(62 miles later). To my surprise, i only got a little over 24 mpg. i was very disapointed because my car is an A4 2.73. (completely stock) This is just after i put in a new fuel filter, changed tranny fluid, changed rearend fluid, cleaned injectors, put in new coil and wire. Needless to say, i was expecting at least 26-27mpg, from what i've read on this forum.

so my question is there any tuning or other adjustments i could do to get better mpg?

i do plan on getting slp cai and totl in may, will this help mileage very much?

 

You're pretty much stuck with the 14.7:1 stock low/part load tuning that is hard coded into the PCM. What you need to do is look at the PCM data to see if perhaps you have some component or defect in the system that is causing the PCM to add fuel the engine doesn't need.... sort of a "false lean" condition. Exhaust leaks before the O2 sensors and misfires are two of the common culprits. Faulty O2 sensor could also contribute. A faulty TPS of MAP sensor might fool the PCM into adding fuel that isn't needed. Sort of like looking for a needle in the haystack, but it should be possible with a good data log of "normal" driving and some WOT passes.

I know when my car was stock (and back when it was an M6), with steady speed 70mph driving, and a reasonable level of discretion with the heavy foot, it would break 30mpg very consistently.

 

basically the only way you can get better gas mileage is to drive slower. i know my car will cruise at 1700 rpm going 65 where an auto is probably 2200ish or near that. eventhough you are geared better for highway driving i still think 25 is decent. i think the best i ever got was 27 with mabye 85% highway driving in my m6.

 

at 70 mph, my car is running barely over 1900 rpm.

what about the cai and catback, will those help out any?

 

ttt

 

the cai and catback shouldn't hurt any and it may help out a bit.

realize that a 60 mile trip isn't a very good estimate of milage

realize that a decrease in gas milage from 27 to 24mpg is only a drop of .3 gallons of gas with such a short trip.

.3 gal could be the differance between filling your car with it on a certain incline, or being on an unlevel concrete surface, or even what could be held in the "filler neck"

the farther you go the more accurate you'll get

think about it:
if you go 60 miles on 2 gal of gas, you got 30mpg. but it you pump 0.1 gal more gas your milage goes down to 28.6, pump 0.2gal more and it drops to 27.3mpg, and 0.3gal more would give you 26.1mpg...

leading you to think you lost almost 4 miles per gallon, when in actuality it may be the same!

 

teke 184:
that's an exellent point. i never thought about the fact that it is such a short trip and small amount of fuel that slight differences in fueling up the car will have a large affect on mileage. i guess i need to make a longer trip to figure the mpg for sure.