So I've had my G for over a year now and there's something that been bugging me. I live in NY so most of my driving is city driving. I've always known these cars get horrible fuel economy so I never questioned filling up once or twice a week. But I noticed something recently.

In the MPG thread, most of you are getting 23-27 MPG with highway driving. With only city driving, I averaged 12 MPG on my last full tank.

Last week I took a trip to the hamptons, filled up, set the cruise control to 65, and reset my fuel economy. I only got 18 MPG on my trip out there, and without resetting it on the way back my average went down to 17. What gives??? Anyone have a similar experience. I promise I stay off the gas most of the time lol.

 

How are the air filters looking on the car? That's one big give away there if they haven't been replaced in awhile. Also cruise control can either hurt or help your MPG in some situations.

 

Tire pressure? Alignment?

What wheel/tires? Sticky and wide tires will cause more rolling resistance hence the lower mpg.

 

With the age of your vehicle, maybe plugs/coil pack making it run really rich, maybe air filter too. There are areas to start since that is way below what I have seen posted. Though I don't usually get more than 21MPG, there are others that average 26 to 27, so I would imagine some cars would average 16 to 17 as well just because that's how their cars are performing

 

Air filters were brand new until 2 weeks ago when I installed a Takeda Long Tube CAI with a near new filter.

I've never averaged more than 18, cruise control on or off.

Well I have 245 fronts and 275 rears but my wheels are much lighter than stock (20 lb front and 21 lb rears) so wouldn't that make up the difference in terms of rolling resistance?

I was thinking that as well. I think I'm gonna get new coils and plugs and see if that changes anything. I've never seen more than 20, which really bothers me when people talk about 25+

 

You have to factor in that you have 9% front and 12% rear wider tires than stock. More surface contact will create more rolling resistance. How significant can it be? I dunno but they have a direct relationship with your mpg. wheel/tire combo weight is another thing. I think you should check your alignment first before changing anything. A slight toe can cause drag.

 

Are you seeing a lot of carbon build up in your tailpipe? I know that after I wash mine the build up is quite noticeable after about a week. Oh, one other thing to check is for dirty TBs. I've heard several claims of boosted MPG after cleaning their TBs. I haven't done so only because I've wussed out not wanting to hit a dealer to fix a TB relearn. But I need to get in there and at least look at them to see how dirty they and the plenum are. Good luck!

 

Is your car AWD?
I've seen some peeps driving with snow mode on. That will impact your MPG and the car will drive like turd.

 

Its probably your spark plugs my g35 was having the about the same mpg and after I changed them it jumped to 18mpg (with me getting on it regularly)

 

Lol @ turd snow mode

Can't be awd due to 6MT.

 

Ouch, that some pretty rough mpg. I run boat-anchor 20s w/ wide 295s out back and the worst I get around town is about 18 and still get 28mpg
hwy.
And that's w/ a pretty heavy pedal .

 

Alignment sheet looks perfect. There's a tad extra neg camber but that's because I'm tracking the car soon.

Yeah, I'm gonna do coils and plugs soon because that was what I originally thought and everyone seems to be confirming it.

Yeah, I don't think it has to do with the wheels or tires, I don't think they can cut my fuel economy that much. I remember getting the same thing on the stock set up.

And how do you fit 295's in the rear. I'd love to do that, my rear wheels can accommodate 295s but I'm afraid of rubbing.

 

You New Yorkers are brave people. Not sure how you guys can drive lowered cars around NY. The roads are so horrible. I remember I bottomed out so many times on stock suspension with all mountains and craters scattered everywhere.

 

I'm lowered on coilovers to about zero gap and w/ 20x10 +45 offset I can run them without any rubbing at camber well in spec

 

I don't even want to talk about it. All of my wheels are bent or have rashes because of the pot holes. My suspension is on the softest setting and it still hurts driving anywhere. I'm planning on moving the first chance I get.

That looks sick. I'd love to get 295s in the back but I dont think it would work with my offsets. Did you have to shave that bumper bracket?