Bhead32

Well i have had my car for almost 4 months now!(since end of october) and have about 2200 miles. I have always been confused with the MPG rating though. It used to be showing an average between 8.5-9.4 mpg and since my Hcap uhh..fell out, the rating is now showing between 9-10.5 average. THIS IS HORRIBLE!! I remember most of you guys saying that you were right on advertised rate of 17-23.

I thought it was a problem with the computer but i did the math myself and discovered that this average is completly accurate! Now dont fllame me for not taking care of it earlier but I have been experimenting with this problem for a while now and have decided to take it in soon.

Also, around 3K rpms usually under hard acceleration in 1st & 2nd i hear a slight rattle comming from under the hood/tranny i think (very hard to pinpoint). Could this be related to the strange MPG problem?? I think the MPG problem could be because the car was tunned a little off or something with the electronic feul injector?? GIVE ME SOME ADVICE GUYS. Thank you

05GT-O.C.D.

Do you drive it like you stole it? I'm sure that when they get those good ratings they're driving like Grandma's in the passenger seat on her way to church.

Bhead32

Yes but even when i try to baby it, i still cant get a 17 mpg. When on the highway at very low RPMs of say 2K i can get ok ratings but still doesnt 10 mpg average seem TOO LOW?? even if I am stomping my foot through the floor?

os121

Check this thread for your question on the noise. Perhaps you have the same thing ?

Link to Missing Bolts and Rattle

OSUstangfan

well, this could be attributed to where you live, alot of stop and go and so forth. As well as if you just make alot of short trips or what not. My mpg is great when im in dallas and go at least 10miles everywhere, but when im at school, everything is less than a mile or 2 away and get horrible mileage.

wild stray

In the city, how soon you shift can make a major difference in mileage.
You might try getting into the higher gear ratios sooner.

SixtySix

I'd be taking it in PRONTO. That ain't right!

My first 2 tanks were my worst, and I was running it hard. The first tank was 12.5 mpg and the second 14.0

Now I average 17.0 combined (mostly in town)

Stubbies

Same advise as SixtySix. If I mix it up between city/highway, I can get 19-20 or better, and even in just straight up city, I only get down to 15 if I am romping on it much more than babying it. Shift points also make a big difference. I shift at like 2500 if babying it, bout 6k if going for performance.

P.S. - I still haven't lost my H trap, this is a completely stock car.

EleanorsMine

in rush hour traffic I get CRAPPY mileage.....I have used 1/4 tank on several occasions just driving 15 miles north and back for Friday night dinner. I do the fun pedal a little too much though, but I know all about that..

Regular open no stop light driving I average about 17 a tank.

graphicguy

I know this won't make you guys feel any better, but in my RX8 (1.3L engine) I get 13 MPG city and am lucky to break 18 MPG in highway driving on the required PREMIUM fuel.

I've actually clocked as low as 11 MPG and as high as 21 MPG, though. That's pretty far off the 18 MPG city and 24 MPG highway it's rated at.

These are sports cars. If you expected sterling MPG, you bought the wrong car.

I guess I'm jealous that you guys have a 300HP engine that runs on regular fuel.

RRRoamer

Rotorys have never been know for their fuel economy. Also, keep in mind that even though it is a 1.3L engine, it fires 3 times per revolution (rotor revolution), which makes it act like a much bigger engine as far as air/fuel is concerned. I'm also not surprised at all to hear that premium is manadatory. The super long and flat compustion chamber of a rotory does have problems with knocking. It's just the wrong shape.

A perfect shape would be a sphere with the sparkplug right in the center. Basically, the most volumn for the least surface area and you minimize the distance the flame front has to travel to reach all corners of the chamber.

The long, flat shape of a rotory is just the opposite. Lot's of surface area and there is a huge differnce in distance between different parts of the combusion chamber. They partially get around this using dual spark plugs that fire at slightly different times, but still is a band-aid. Of course, the rotory DOES have all those weight/smoothness advantages going for it!

Bhead32

I hear what all of you guys are saying but I do not think that everytime I reset my MPG computer it should always average out to roughly 9.7 (with the Htrap in). I know it is a sports car...thank you. I also do not expect "sterling MPG" I expect to get what everyone else is getting which is around the advertised rate of 17MPG city. Regardless of how I drive it, it NEVER gets to be 17 mpg unless I am in 5th on the highway. Shifting at low rpms, stop and go, and not accelerating hard does not matter because the fact is: There is a problem with my car. Now my question is what could cause this absurdly low MPG (obviously besides the way I drive)?

Altoid

Take it in, if you really aren't pushing it and getting that kind of mpg there must be something wrong.

graphicguy

RRRoamer....yeah, the rotary does have some advantages. Winging it to redline at 9K is one of them. The rotary "wakes up" about the same time the Mustang is hitting it's peak. That said, the RX8 has surprisingly good pull down low. The sounds it makes are exhilerating as you wind it out and see the digits of the speedo go by so fast they're a blur.

But, the Mustang GT's V8 is intoxicating in it's own right. Plus, it's faster (not that the RX8 is a slouch in the speed dept).

The '05 Mustang is the first one in a long time that has me smitten with it....kind of like that girlfriend you had a long time ago who had those perfect lips and that soft as silk kiss (sorry, didn't mean to turn this into a "****" post).

Back to the topic at hand, if you're only getting 10 MPG in your GT, if you're certain about the quality of your gasoline, then something's not right either with OBDII (in which case you'd be getting a check engine light), or something's not right with the PCM.....just a guess. How does it run? Any "blips" or hesitations as you run it up through the RPMs? Getting any backfiring through the exhaust?

As a side note, I've been using Costco gas for the last 3 or so years and have been very satisfied with it (plus, it's usually cheaper than any of the stations around me).
And, my car is particularly sensitive in the quality of fuel it gets.

Dealer should be able to hook it up to their computer and tell you exactly what's going on.