1994 Intrepid, 3.3 flex fuel, 204,000 miles
15 city and 30 highway, so the average would be 22.5 mpg. I drive like an egg was under my foot. Gas isn't getting any cheaper.
Steve

 

I'm trying to get to the bottom of my car's mileage problem... the mileage is 17-19mpg max on the highway, running even 93 octane. I did get 23mpg for a fluke when running 93 *and* fuel system cleaner, but without the fuel system cleaner the mileage drops again.

So far I've done the spark plugs since it has 65k miles, and the transmission flush.

 

I get 25-27 with my driving style. I like to hover around 55-65. I usually accelerate quicker than most well say. I have a 2001 2.7L. I believe we got about 30 mpg driving to my college in Ohio. I dont know how you guys get good mileage with your cruise control. Mine, you can just watch the needle move down when cruise is on. Thus why I dont use it.

 

First off I would stop using 93 octane. Regular fuel is fine. Second, I would switch to synthetic oil.

 

Wow, what a topic starter!! First I'd like to say I have a 97 3.5 and get from 23-29 MPG with a lead foot. I use mid-grade fuel and clean the injectors with a can-o-stuff ever now and then. I change my fuel filter periodically and also the air filter. The air filter can cause poor mileage and can dirty up fast in some conditions so the K & N spray and lube type is nice but expensive. I have always just used the cheep throw away kind, if this is what you use make sure to change often.

From my experience (other than driving habits) the major contributors to poor fuel consumption are:

1. Dirty injectors and fuel filter
2. Dirty air filter
3. Weak spark
4. Poor compression

If the car isn't malfunctioning, then the answer must lie in the filters & injectors. While gas is also important, it isn't as important as some believe. I live near a CITGO gas terminal (where the barges bring the fuel in) and nearly ALL the gas stations use the same gas!!! I spoke with one of the drivers and asked how they fit all the different grades/quality fuels on the tanker and in the terminal tanks. He chuckled and said “it is the same gas for nearly all the stations; they just add their secret ingredient prior to filling the truck" (I think there was 1 he had told me that actually trucked in their own blend). This is the trade mark of all fuels, their additive. To me, it's just as well to add my own favorite cleaner additive and buy the cheapest gas on the market! Some don't like to go to that trouble and just pay the higher premium at the pump.

As for octane, yes higher compression engines require a higher octane or they will PRE-detonate (octane is a retardant and makes fuel LESS combustible but is required with higher compression engines or you get the pre-det knock). The 3.5 engine has a nice feature many don't know about called a "knock sensor". What it does is if you are running a cheep low octane gas, it retards the timing so the engine is less likely to pre-detonate. Of course that also translates to less performance and the adjustment can only do so much.

Any way if you really want to run better performance I heard from a friend about a kit to mix hydrogen to the fuel/air mix which will give a 40-50% increase in MPG, and increase torque/power while decreasing emmisions! I have not done any research to confirm or deny it, so if any happen to try this new tec., please post it!

New eddit..........

Here is one link the the hyd kit I mentioned above.
http://www.greencarcongress.com/2006...e_begins_.html
Kurt

 

Are you insane doing that to a 2.7?!
That engine was poorly designed and NOT made to throw that kind of weight around...
There's a better kit than K&N... http://www.dodgeintrepid.net/ Ask JoeKD or go to http://www.j-intakes.com/

My car when floored all the time gets 25 minimum. It's amazing when it's about a ton heavier than regular civilian cars. Police package!! 3.5L High Output, JoeKD intake.

 

i aint drove it much but i put 4 gallons as soon as the gas light came on, i have went 53miles and the gas light is almost on thats 13.25mpg!!! i drive it pretty aggresive, its a 95 3.3l with 124k on it, i just changed oil 4 days ago, havent checked anything else cus i got a wobbly sound coming from the tranny, but the tranny was rebuilt in feb at 113k, the kid just beat the **** outa this car and i think the flexplate is wobbly now. but this car is a dog on gas!!! wtf i traded a 90 honda civic 4 door new motor for this, sorry guys these cars look sexy and drive sweet but they are pos cars, bad trannys, bad milage bad oil leaks, lol, my v6 GTU chevy BERETTA was way bad too it got like 14 no matter, and it had the stupid mpg gauge to insult you that it was for sure!!!lol but this car says its supposed to get 20-28mpg wtf!!

 

It souds like the kid ripped you off lol!! Did you every do a compression ck? Kids who "beat the ****" out of cars, usually sell them when they notice a drop in preformance or increase of repairs. If you put the time and $ into repairs, (to include that "wobbly" sound), I'm sure your new car will do just as well as ours!

 

it drives sweet, plenty of power, it was actually his moms car, she had it rebuilt, he wanted rid of it for a honda, and when it started making the noise he really wanted rid of it, just like as soon as my timing belt kept slipping at 5grand and my clutch was slipping at 4 grand i wanted rid of the honda too
i notice the air box screws wont open so im geussing that dirty as hell, i just dont want to pull no more damn trannies, and these gotta be heavy as hell!!! but if the flex plate is bent or cracked i got little choice...im going to get it up in the air here in a few hours and pull the inspection plate and see what i can see

 

I have the ES with all the bells, today while on a rod trip I thought about your problem and thought I'd take a few notes, they may be insightful. While on an open road, I set the cruise at 65 and monitored the real time gas consumption via theoverheadcomputer(this is a lot slower than I normally drive, so the consumption rate is a bit higher than my normal). At @ 2K RPM, 65MPH, and on a moderately flat road, I was between 32-38 MPG. I normally drive faster and also with a lot of city traffic, so the average stored in the computer for my car is 23 MPG.When I have taken road trips in the past with the monitoring computer reset, (also resisting the urge to exceeded 65 MPH), I got 32 MPG. It my be if your engine is fine, your poor gas performance comes from the shifting side of the house. What do you have? Auto trany, stick, an onboard computer or without one, RPM gauge, ECT and what drive conditions?