View Full Version : OMG this is crazy I'm getting about 9.5 miles per gallon help plz


desiz
04-19-2009, 12:39 AM
This cant be possible at all cause I mostly grandma my car and switch gears at a maximum of 6000 rpm. I use shell v power. btw I got my car recently. Can someone please tell me whats wrong and why i'm getting terrible mileage. Also mostly 90% City Driving.

cjkim
04-19-2009, 12:44 AM
year? updates done? any other symptoms? low on power? plugs/coils changed? have you gotten the recall? your description is way too vague.

nycgps
04-19-2009, 12:45 AM
Make sure you have insurance first.

then Run your car into a wall @ 35 mph. total it

get your money back, move on.

case closed.

desiz
04-19-2009, 12:48 AM
year? updates done? any other symptoms? low on power? plugs/coils changed? have you gotten the recall? your description is way too vague.

I recently completed all the total recalls and updates at my local Mazda dealership. My car has about 35k so the dealer said the plugs and coils are fine. Its a 2004

cjkim
04-19-2009, 12:53 AM
I recently completed all the total recalls and updates at my local Mazda dealership. My car has about 35k so the dealer said the plugs and coils are fine. Its a 2004
your dealership may be right...
more likely wrong though. pull your plugs and find out
check air filter
pull room fuse

now if you're shifting at 6k every single shift in the city, i wouldn't be too surprised.

desiz
04-19-2009, 12:57 AM
your dealership may be right...
more likely wrong though. pull your plugs and find out
check air filter
pull room fuse

now if you're shifting at 6k every single shift in the city, i wouldn't be too surprised.


I checked the air filter my self, and i thought 6k 1st and 2nd gear was average in the city. Where is the pull room fuse?

desiz
04-19-2009, 12:58 AM
....Guess i'll have to bring it to the dealer on monday :eyetwitch

AndrewE
04-19-2009, 04:22 AM
I used ot get about 250km/160mi to a tank all city, and my car was fully tuned up(plugs, coils, air filter etc), also an 04
Now I get about 400 tank mostly highway, some city(80/20)

zoom44
04-19-2009, 12:08 PM
first has to be asked what is asked of everyone with this type of post.

how are you calculating your fuel mileage?
2nd how many miles and minutes is your average trip?
where do you live?

spence15
04-19-2009, 12:16 PM
lmao 6000. I don't think thats helping. I know the manual is hardly a bible but read up on when to switch gears. It's something ridiculous from what I can remember. You should definately see an improvement. Although your car will be a turtle accelerating. I don't think I could get this bad mileage if i tried,

do you accelerate really fast and then slam on your brakes over and over again in the city?

...And you do know you own an 8 right. You could always get one of those KIA's or Honda fits I hear they have excellent mileage.

desiz
04-19-2009, 02:02 PM
first has to be asked what is asked of everyone with this type of post.

how are you calculating your fuel mileage?
2nd how many miles and minutes is your average trip?
where do you live?


After each fill up at the station, I reset my trip odometer, on average I get about 152 per tank. Then I just divide that by 16 which is how much the tank can hold.

My average trip is about 15 min or 5-8 miles. I live in the suburbs of chicago, so not hilly or anything like that. I also do not slam the breaks at all.

cjkim
04-19-2009, 02:20 PM
After each fill up at the station, I reset my trip odometer, on average I get about 152 per tank. Then I just divide that by 16 which is how much the tank can hold.

My average trip is about 15 min or 5-8 miles. I live in the suburbs of chicago, so not hilly or anything like that. I also do not slam the breaks at all.

WRONG
divide by the amount of gas you PUT IN! you'll almost never get 16 in. I usually get in 13 or so.
Good point zoom, didn't really think people were calculating their mpgs incorrectly..

5-8 mile city trips also don't help. are you new to manual trannys? 6k shifts are pretty speedy get-gos.

tsxmidship
04-19-2009, 03:08 PM
steps to find gas mileage:
1. Have a FULL tank of gas.
2. Hold down the odometer reset button until the odometer reads 0 miles.
3. Drive like you normally do.
4. Realize that you need to put gas into your vehicle.
5. Drive to a nearby gas station.
6. Pump gas.
7. Look at gas pump and see how much money you owe for the gas you just pumped.
8. Pay for gas.
9. Look below the amount of money you just paid on the gas pump and you will see the amount of gasoline you pumped, usually in gallons. Write this number down.(Call it A)
10. Go into car and look at the odometer reading. Write this number down.(Call it B)
11. Take number B and divide by A. (ie. B/A) Write this number down(Call it C).
12. C is your gas mileage.
13. Repeat steps 1-12 to find new gas mileage.

Razz1
04-19-2009, 05:39 PM
WRONG
divide by the amount of gas you PUT IN! you'll almost never get 16 in. I usually get in 13 or so.
Good point zoom, didn't really think people were calculating their mpgs incorrectly..

5-8 mile city trips also don't help. are you new to manual trannys? 6k shifts are pretty speedy get-gos.

:eek:! Simple math.

:beer05: :beer:

zoom44
04-19-2009, 11:41 PM
After each fill up at the station, I reset my trip odometer, on average I get about 152 per tank. Then I just divide that by 16 which is how much the tank can hold.

My average trip is about 15 min or 5-8 miles. I live in the suburbs of chicago, so not hilly or anything like that. I also do not slam the breaks at all.

guys dont be too hard on him everyone has to learn some time.

ok so first fix your math as others have said above divide the miles by the amount of gas you buy. most fill ups after the light comes on will be 13- 13.5 gallons if you head for a station soon after the light comes on. using 13 you're getting

152/13=11.6

take your shifts down to 3k with the occasional run up to 9k AFTER THE CAR IS FULLY WARM. by shifting at 3k you should be able to stretch a tank to 160 or better.

that should get you to 13mpg or a little more. with your short trips and the oxygenated gas your losing allot of mpg. your short trips keep the car in open loop most of the way which is just less efficient then closed loop. as much as 15% less. the oxygenated fuel can also cause the car to be up to about 20% less efficient.

now you dont add those together to get the whole loss but those to together could account for 20 - 25% less mpg from the sticker. remember under the revised new EPA rating system the city MPG is 16.

16 * .8 = 12.8 :)

Does chicago lose the oxygenated fuel in summer? if so you might make it to 13 during the summer if you shift sooner.

hope that helps.

ASH8
04-20-2009, 02:05 AM
MAF Sensor, or clean?

DOMINION
04-20-2009, 02:45 AM
I'm getting anywhere from 16.2 to 17.2

swoope
04-20-2009, 03:59 AM
wow,

this is the test you need to try..

get a map.. find the intestate.. not the traffic jamed on.. but the one where you can drive not in traffic. like for hours..

when you find it.

pull into a gas station, fill the tank up. then pull the room fuse.. the info is in the owneres manual in the glove box.

drive the car on the interstate for at least an hour.. two would be better. then drive back to the gas station you started at. fill it up and get back to us..


beers :beer:

cornholio135
04-20-2009, 12:41 PM
I would clean the MAF as suggested... I get 200 miles on 3/4 of a tank... average about 18-20 mpg... mixed city and highway... redline frequently...

kersh4w
04-20-2009, 01:27 PM
i get 240 miles to a tank on average. 30/70 city/highway.

i've seen 295 miles before.

generally 13-13.5 gallons per fill up.

Razz1
04-20-2009, 04:10 PM
I get better than this with my vette motor in my G8 GT.

rotarygod
04-20-2009, 04:31 PM
The worst I get in an RX-7 is 18 mpg but can often get 20-21 in regular driving. It's still a rotary so it's relevant. I know many who can't get that in an RX-7. I drive just as Zoom suggested. I shift at 3000 rpm. Why anyone shifts at 6K daily driving and then wonders why mileage is bad is beyond me. Even with a low rpm shift point, it's typically no problem keeping up with traffic. I shift into higher gears as early as possible and will actually cruise at 30 mph in 5th gear (6th for you). The engine will do it just fine. I have also learned how to anticipate redlights. If I see one way up there and it's been green a while, I know I probably won't make it. I let off the gas very early and coast in. I see many people stay on the gas for far longer than they need to. I'm not a road hazard by any means. Keep in mind my car runs pig rich too. I'm hoping to get it leaned out so I can average a consistent 21/28 mpg. It's possible and maybe even a bit more on the hwy mileage.

I know some would say that driving the way I do is just asking for carbon buildup. I don't have much of an issue. First I do rev it up at least once a day. Sometimes more but of course I know the more I lay on it the worse the mileage will be. Sometimes fun is worth it. Typically I'll accelerate hard through first and second. This gets the engine under load at some nice rpms but keeps you within the realm of the sane when it comes to speed on surface streets.

I also like to steam clean my engine every other oil change. This too keeps the carbon away.

nmarz77
04-20-2009, 04:36 PM
I used to get 12 mpg in the winter months and 15 mpg in the summer. After changing my plugs and coils(at 30k miles) I now get 15-16 mpg in the winter and 18-19 mpg in the summer. Also like others have said, try to keep your revs below 3,000 rpm.

zoom44
04-20-2009, 09:24 PM
dang texans dont have oxygenated gas :(

sheeblue01
04-20-2009, 09:42 PM
I get better than this with my vette motor in my G8 GT.

You dont have a "vette" motor in your G8 GT

Now if it was a G8 GXP you would

Put that L76 in an RX8 and it would prolly get like 34 mpg.

I am looking at buying an 8 and I would like to get decent gas mileage out of it.

ASH8
04-20-2009, 10:21 PM
Keep your REVS Below 3000 RPM!...are you serious???, what is the point of a rotary...

You would be *Choking* it to death..

In an Auto it would be easier, but a manual would be utter driving frustration it would be as slow as a slug unless you kept it in 3 rd gear.

I get around the 20 MPG most of the time...sometimes better, just a little.

ASH8
04-20-2009, 10:33 PM
I guess though in reality a lot depends on your local conditions, I get on a one way expressway that goes for about 30 miles without any lights or stops..(top speed is 100KM or 60 MPH) most go faster, but we have lots of speed cameras (portable).

Return journey more lights, but the opportunity to Rev it out a little, but I suppose on average if you "obey" traffic laws the 3000 RPM range would be the average, for me City Driving is a pain with a stick and the 8.

I guess I am lucky I live in the Outer Suburbs with great roads, less traffic and lights.

shazy
04-20-2009, 10:38 PM
I get 265miles to the tank 50/50 city/highway driving :)

zoom44
04-21-2009, 12:01 PM
ash what the point of having it at a higher rpm if you are just going about local roads behind others going 35 mph? your just making noise and running out the fuel. when you need power you shift- thats why you have all of those gears in the first place, right?

dstolp
04-21-2009, 12:57 PM
Does the room fuse apply to all years? I did a search of the 05 owners manual PDF and did not find "room fuse". Not sure what this is suppose to do so not sure what else to look for.

cjkim
04-21-2009, 02:27 PM
Does the room fuse apply to all years? I did a search of the 05 owners manual PDF and did not find "room fuse". Not sure what this is suppose to do so not sure what else to look for.

look for a fuse labeled room in the drivers side fuse panel

ASH8
04-21-2009, 03:17 PM
ash what the point of having it at a higher rpm if you are just going about local roads behind others going 35 mph? your just making noise and running out the fuel. when you need power you shift- thats why you have all of those gears in the first place, right?

Yes., however, this is my opinion based on owning the 8 for a BIG 6 months, with the higher diff ratio. And this also comes from a dealer tech, "driving the 8 under 3000 RPM all the time is an engine killer", and I am not going to rant anymore about that one.

He had a customer with a new 8 that would not go above 2000 RPM, she thought she would blow up the engine..:lol:

In this country state governments are REDUCING limits.
Why, it is a revenue raiser for them (speed cameras), two it is reducing the Death toll on our roads. In less than a decade road deaths have reduced by 2/3 thirds...and cars are safer too.

You get used to an area, they changed the signs down 10 KMH, catch more drivers speeding.

We have gone from a country limit of 110 KMH (66 mph) to now 100 KMH.
Suburbs from (default speed) 60 KMH (36 MPH) to 50KMH (new default) (30 MPH)
Some council areas are now 40 (KMH) or 24 MPH).
School area's 25 KMH (15 MPH)

There is no pleasure driving an RX-8 at 25-30 MPH max limit at all no matter what gear you are in...you are in the wrong car. BTW I get around 440 KMS a tank or 265 miles.

dstolp
04-21-2009, 03:21 PM
OK found the fuse. Still don't see what influence a 15A fuse for the interior lights has on fuel economy when compared to running the AC or other power hunger accessories.