Poor MPG - Low Mileage and hitting 16.7 MPG on HWY

i say don't worry about it.. i get 24mpg on my g35 coupe which i sold, and now average 18mpg on my fx.. remember, this thing is fat and heavy compared to the the g.. i figured if i wanted better mpg, i'd get a scooter.. :smile (2):
 
SilverStreakFX said:
Update

I actually live in the east bay (Dublin, San Ramon) so relatively flat here

I drove 300 miles and filled up with 18.3 gallons. Makes my MPG is 16.4. Computer actually showed 16.9. I made sure not to drive to aggressively so I am really scratching my head why I am getting so low MPG
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ya... I'd be investigating as well.
Highway / Flat terrain / conservative driving ..... around 20 MPG would make more sense.
 
Only thing I can think of recently is the wheels I out on. 20x10s. Roughly same diameter and they are wider but may be slightly heavier. I didn't get a chance to weigh them to see. I don't see that causing a dramatic difference
 
How often do you fill up? Try filling up close to an empty tank. I found that my mpg is a little better when I fill up from E rather than filling up from a half or quarter tank.
 
I use the aCar app on android, You put in all the info when you fill up and you get automatic mpg and other calculations. I get 14-15 most of the time but I drive 10-15 minutes to work with a lot of lights and hills.

If I do a longer trip like running up to big bear in the winter it does a lot better. I got like 18-19. I think the 23 or whatever would only be on flat highway driving at like 60mph or something. I was following a friend who was towing a trailer so we drove on the highway at like 55-60 mph, and my real-time mpg was really high. also whenever my wife drives the car she gets better mpg than me.
 
SilverStreakFX said:
Only thing I can think of recently is the wheels I out on. 20x10s. Roughly same diameter and they are wider but may be slightly heavier. I didn't get a chance to weigh them to see. I don't see that causing a dramatic difference
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Well thats your problem. Those wheels could easily cause the change in MPG you are seeing. I can see 19-20 MPG on the highway, with my average city/highway being about 18.5 (Bone Stock).

Check you tire pressure, but having bigger heavier wheels IS going to impact your MPG.
 
I used to have a similar problem on my 03 AWD FX35. I was suspicious of sensor issues, and upon replacing both cam position sensors and the crack shaft position sensor, I suddenly get 23-24mpg on the highway, which kinda blows me away.
 
I can't believe nobody said this yet...

Do you drive with the A/C on?

When I drive with the A/C it reduces my mpg by 1-2. Driving with A/C plus your new wheels could easily drop you by 2-3 mpg if not more...

A small modification to your intake (k&n and/plus z-tube) could get you back 1-2 mpg, more if you add a plenum spacer...
 
Make sure you are checking your tire inflation, that is an easy MPG robber. Might not be a bad idea to have the O2 sensors checked out just in case, even if one is bad that will choke gas mileage as well.

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Make sure you are checking your tire inflation, that is an easy MPG robber. Might not be a bad idea to have the O2 sensors checked out just in case, even if one is bad that will choke gas mileage as well.
 
AC is known to lower MPGs. But 16 is pretty good city only. You must drive like my granny..... ;)
 
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