Well geeze.. I would've thought downgrading to a 3.0L 220hp car would help ease the pain at the pumps since my '03 Acura TL-S (260hp) only got me 13mpg. I don't drive crazy and I drive slow too. Only getting 15mpg on this '03 GS3. Anyways, I've searched the forums and read around. So now, I'm just accumulating a list of things to get for maintenance. Maybe you guys can help me out here!

I tried Lucas Oil fuel injector cleaner and it worked but only on one tank of gas. After that, my mpg returned back to crap. It also triggered a CEL, P0141 (Bank 1 Sensor 2) which is basically one of my O2 sensors. After the gas was near empty, the light dissapeared so it seemed like the additives from the Lucas Oil fuel injector cleaner was causing it.

My tires are also properly inflated at 34 psi. Pump 91 only! I also cleaned the intake filter as well. Previous owner stated that the major timing belt service has been done about 30k ago. Here's what I plan to do in terms of maintenance (some parts don't apply but im doing it anyways since im at 150k):

- seafoam
- clean throttle body
- oil change
- oil filter
- replace spark plugs
- replace fuel filter
- flush atf
- flush coolant
- replace air filter
- replace cabin air filter
- replace bank one sensor 2 O2 sensor

I plan to do the above in the order that I listed. Any order you guys would recommend? Thanks for any info or help!

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For reference.. a quarter tank = 40-50 miles. A half tank = 80-100 miles. A full tank = 180-200 miles. Sucks to be me!

 

gs300 is a gas hog in city driving. i think i get around 16 mpg at 100% city driving. i do way too many short trips, less than a mile.

 

I have 220 miles on my 98GS3 with another 1/4 tank to go. So I would say you either got a lead foot or something is amiss.

 

i also average about 225 give or take and still have a quarter tank left and i also have a sd gs3. maybe you drive in sports mode?! that might affect mpg

 

that is totally true. i drive mostly city as well since i commute 6 miles to and from school. but even then, thats just unacceptable for an i6. i've seen people with gs4's go 400 miles on a whole tank.. thats just embrrassing.

like i stated. i dont drive crazy or fast. i try to drive as most fuel efficient as possible and i still get crappy gas mileage.

nope, i drive in regular mode, which is d4. power ect is off and vsc is on. everybody thinks im crazy when i tell them i drive slow and still get 15mpg. yeah, beats me. i guess i'll have to see after doing maintenance.

 

Our cars got a 5-speed transmission, D4 is 4th gear not over-drive.

 

ah thats right.. well i meant to say regular gear, drive.

 

do you have bigger wheels on it as well? bigger tires?

 

lol I once got 200mi from F to 1/2 from DC to Atlantic City. These cars are just weird like that..

 

How long do you let your car idle after cold starting it?

Try driving without A/C.

 

i get 220 and 1/4 left. i thought I'm the only one has the same problem.

 

my gs430 gets 20mpg with 60% highway and 40% city.

 

no, stock 16" rims.

i let my car idle for approximately 10 minutes on a cold start. and i never drive with a/c unless i have to. a/c on or off, it's the same. i get crappy mpg either way.

 

There's your problem. Letting the car idle for 10 minutes at 1400 RPM isn't going to help. You're getting 0 MPG.

 

wow... I would do everything on your list, I recently did all that, MAF, throttle body, plugs, fuel cleaner,etc..

I get and average of 20-22mpg, depending on how much city driving I do, the lowest I have seen is 20mpg when I idle the car a bit.

I am at 275-280 miles with a 1/4 tank left, lights usually come on a little after 325miles or so.