I picked up my G35 coupe about a week ago, and filled it up on the day I got it. It is now a week later, and I'm sitting at about 186 miles, with the time for me to fill up again is approaching. I think that is a problem. When I filled it up, it took 17 gallons, so that means right now I'm getting like 11 miles to the gallon.. that seems like a problem. No warnings have come up on my gauge display thing, so what can I look for/check to see if there is a problem? Granted, it is a fair amount of city driving, (maybe 80/20 : city/highway) but still.. 11 miles to the gallon? a 5.7 hemi probably gets better mpg than that.

 

If your filling 87 your most likely to get 11 MPG, try filling 91.

 

87 is regular right? If that's the case I did fill it up with 87. It was my first fill up and I didn't want to burn my wallet on the first day

 

Using 87 Octane gas won't cause THAT drastic of a fuel economy drop.... maybe like 1-2 MPG less than using the proper octane. He should be getting closer to 16/21 MPG City/Highway with his car if it's relatively stock unless he's driving it like it's stolen, and should be getting much better than that with lighter more fuel-efficient driving styles.

To the OP.... I'm not sure how many miles there are on your new car, but you might want to start out doing a full tuneup on it. While you're at it, clean your MAF Sensor and run a container of Chevron Techron fuel system cleaner through your tank the next time you fill it up with gas, and check to make sure your tire pressure is where it should be.

 

I definitely don't drive it like it's stolen other than the few times I feel like being a douche and stepping on it a little bit to make my girl's panties wet. But at the same time, I don't drive it like a grandma.

 

True shouldn't make that big of a difference didn't think about it i guess -_- lol, but yeah go 91, and drive it with respect. (:

 

Woah woah.. one step at a time lol... kind of a noobie here.. my car has 72k miles... and what exactly is a tuneup?

 

Haha... you really must be a Noobie if you don't know what a tuneup is! LOL.

I'll let it slide just this one time, but don't let it happen again!

Basically, you should probably do the following:

-Change Engine Coolant
-Change Motor Oil and Oil Filter
-Change Spark Plugs (Even though they're rated for 100K on these motors)
-Clean Mass Airflow Sensor
-Inspect and possibly change/clean Air Filter
-Change Transmission Fluid
-Change Differential Fluid
-Lift each corner of the car and make sure the wheel turns smoothly and that you don't have a sticky caliper or worn wheel bearing.
-Check your brake pads to make sure they are within spec and replace them if not.
-Check and set tire pressure to spec.... usually it's 35 PSI on stock tires/rims in a G35 Coupe

Is your Check Engine light on? If it is... pull the code using an OBD-II scanner and use that code to determine what the problem is, and fix it. Things like faulty Oxygen sensors will cause your Check Engine light to come on (amongst many other things), and can drastically impact your fuel economy in the negative direction.

Also... make sure that your car is heating up to full operating temperature. If your thermostat was stuck closed, the car would take a very long time to reach full operating temperature and this would make your fuel economy remain pretty low throughout the duration of time in which it was not at full operating temperature, while also accelerating the wear on your Catalytic Converters.

By the way... welcome to the forum, and hope you're enjoying your new car aside from the poor fuel economy you've been experiencing!

 

I take this to mean that you haven't yet filled it a second time? Fill it again and see if that's really your gas mileage. Fuel gauge problems aren't so unusual with the G's. I've pulled and cleaned the sensors in my gas tank twice in the 8 years I've had it...

 

I was getting around 14 MPG last year until i found out that i had a stuck caliper. Now i'm around 17-19 in the city. So that's something to check. Running anything less than the best fuel you can buy is doing injustice to your car. @ 17 gallons and 20cents more per gallon youre only spending an extra $3.40. Come on big baller you have a sports luxury car now

 

Thanks a ton, and thank you for sparing me and my noob unless haha

If I understood your last paragraph correctly, I do drive the car while it is cold. I usually don't have time to heat it up before driving so it is a lot of turn on and go. If that is what you meant, then I guess I'll take it more into consideration, especially considering its been extrnely cold past couple days here in jersey

 

Thanks for all the helpful tips guys, and I'll take them all into consideration.

And I am a big baller haha it was just that it was the same night I got my car. I know better now

 

When it's really cold outside, you want to let your car warm up for about a minute or so before driving off, but don't drive it hard while cold until the temperature gauge reaches the middle of the gauge and stabilizes. You don't really want to let your car sit there idling and warming up for extended periods of time... plus that won't help your fuel economy anyways. What I was referring to was the cars internal thermostat. It controls how the car allows coolant to flow into the engine from the radiator. If your thermostat was stuck open (meaning it was bad, and needed replacement), your car would take forever to warm up because the cooling system would constantly be trying to cool the car off even though it is supposed to be allowing it to warm up. Cars run very inefficiently during the warmup state because the fuel mixture is very rich and all the fluids are very thick and resist the rotational inertia of the moving parts that they come in contact with (motor oil, tranny, and differential fluid for example).

 

Thats cold weather and the G for ya. In the winter I get MAX 16 MPG. It normally hovers around 12. Summer I get about 18-19. I wouldn't worry about a tune-up unless you can do it all yourself and save some money. Wait for Summer and your fuel economy will be better... It DOES help to only let the car warm up about a minute before driving (gracefully, no showing off until its warmed up) away.

 

Grr. I hate winter. i think i might get it checked out and tuned up either ways, seeing as its my new car and idk how well the last people took care of it. how much does a tune up usually go for? the car is under warranty but im not sure it covers tune ups. any ideas?