gen1xslugger

iv filled my new 01 tib 3 times now... each time getting around 18.5 mpg....

car is stock and i dont drive stupid. (dont accelerate faster than needed, slow down when i know i wont make light, all the normal stuff to get better mpg)

i know i SHOULD be gettin 23 or so mpg.

any ideas whats up?

AGreen

Is your car an automatic? Either way, 18mpg sucks. Try having a fuel system service done professionally. Make sure you get your maintenance done such as fuel filter, spark plugs, wires, oil changed, transmission fluid changed, air filter clean, tires properly inflated, tires balanced, make sure suspension components aren't worn out, etc. Make sure your battery cable ends aren't corroded, and that all grounds are good. Driving short distances to and from work/school hurt mileage, especially if you get there before the car heats up completely. Fill up with regular octane as well. Also, I've heard that RD2's will automatically turn on the A/C when it's in the defog mode, which sucks mileage also. 23 mpg sucks too. More like 32 is what I usually get.

Your check engine light isn't on is it? If not, are you sure the light bulb isn't burned out? You can check that by turning the engine off and turning the key on to check for the light. Just verify there aren't any codes in the ECU and that the maintenace is kept up on it.

daafisch

Yeah basically make sure your up to date on all your maintenance stuff is up to date as AGreen said.

And im not 100% sure but I believe most cars have the A/C on when in defog mode, at least i have been told that.

Bullfrog

OK here is a standard round of questions.

Mileage?
previous work done by previous owner?
performance issues (stuttering, stalling, hesitation)?

Sounds like you need a tune up.
Spark Plugs, wires, fuel system flush or treatment, sea foam your engine, take your car to a part store and see if you have a code stuck in your ECU but not throwing a cell.

Go to the search box and type in with the quotes "tune up"
any key word with quotes will lead you to the promised land most of the time.

good post on this to get you started
http://www.rdtiburon.com/index.php?showtop...2;tune+up\

I know that the most noticeable will boost your MPG but most of the stuff is good to do for peace of mind.

gen1xslugger

yes automatic and has 37800 miles on it. iv had car for roughly 2 weeks. supposedly all is up to date... im goin to dealership for my free wash this weekend, maybe i can have them check it out

also, no bulbs are burnt out so the check engine light IS off.

netsniper

Listen I get about 250 miles to a full tank depending on how I drive and depending on where I get gas at. Being that the motor has a 10.3:1 compression ratio shouldnt you be filling up on medium grade fuel anyways? I have seen a noticable performance and mpg difference between both 87 and 91 octain.

I would also recomend a complete tuneup including a tranny flush being that the car is almost at 40k and I dont think the previous owner would have had it done.

njsharkracer

don't forget either that we are running winter grade gasoline right now that is highly oxygenated and that usually gives you some form of a mpg hit, but not that drastic. I have a lead foot and do mostly city driving, and I still get around 22-23mpg at this moment.

netsniper

yes I did notice that the winter crap gas does suck on mileage but I am pretty much WOT most of the time and a second note for best fuel economy keep the tach at about 2500rpms anything lower than that you will suck down fuel and anything above 3500 your killing your mpgs and over 100mph forget it... you have the the same fuel economy as a h1 hummer maybe a little less

zoned019

You should be getting like 25-30. I drive spirited, and I get about 26. If it's all highway, I'll get 30+ sometimes.

Here are things you can do..
AutoX Oil Treatment
New spark plugs (if you can afford it, I'd get plug wires too. stay away from Nology's though)
Run some B12 Chemtool in your gas tank
Run some Sea Foam through your intake to clean up all the gum
New air filter (if you can afford it, I'd just buy an AEM CAI)

Lastly, this made a NOTICEABLE increase in gas mileage, and people claim it also makes a noticeable increase in performance
1.8 ECU mod...this probably raised my MPG by like 5 alone. The $60 I paid for it I saved in gas in probably 2 months.


Search for any questions on any of that stuff, it's all been covered before