i have a 2007 gs 350 and im getting only 14 mpg. what may cause that? and i'v had no indication that there is a malfunction.

 

uhhg, wrong section dude.. try 3rd Gen forum

 

I have the same problem. What I do to get better mpg is fill up b4 you get on the high way then I'll get like 18-24 but if I fill and drive local I get 12-15

 

Lots of stop and go? Heavy foot? Winter fuel? Lots of variables can cause irregular m.p.g. Is this a new issue?

 

Dont look at the MPG from the monitor. Fill up the tank then reset the trip, drive until the light go on let see how many you got. I got 14 for local, sometime 29 on highway but mostly 20 or 24 on highway. so at the end when the light gone on. I got 340 miles from full tank to the light pop on

 

simply ....whats ur fuel trims....
stft and ltft on idle and on 3500 rpm


u need a scan tool,, any cheap one will do it

regards,,

 

I'm getting around 16-18 city and I have a 430. I'm a grandpa when I drive though. I expected a little better from the 350. You should be able to out do me big time though on the highway.

 

^ all depends on driving conditions. Your city driving might be a lot easier than his city driving.


OP is in CA, if you're in a lot of stop & go, lots of traffic lights, etc 14mpg sounds about right.

My work commute is 1 mile, with 4 stop lights. If all i do is drive to work for the week i average 13 mpg

Mix in a little highway and the MPG's go up rapidly

 

I have an 08 GS 350 stock with 18" wheels
Consistant 30-32 on freeway at speeds of 70-80 avg.
This is what the onboard mpg shows and also confirmed when filled up, miles driven divided by gallons used.

I don't watch in town much but if it was 14 or so avg. I would have to think something is off.
Larger heavier tires and wheels will hurt milage for sure but 14 is what my 5000Lb. 450 HP at the wheels 15 psi blower pressure modded 03 Ford Lightning gets.

 

Frankly, I would say that only a handful of folks that own this model ever heard of STFT or LTFT. Not likely they have a scan tool to post those numbers either. Good suggestion, though.

OP, a visit to the dealer could help shed some lights. They can check your Short and Long-term fuel trim, DTC codes (if any), etc. But start with the basics. Check your air filter and depending on your mileage, plugs could be due.

My GS gets about mid 20's with a mixture of driving. I can easily hit 30mpg on long highway trips, too. Not once have I been in the teens.

Good luck.

 

I have a 06 300 stock just k&n filter and I'm touching 24 and the most I hit for approx miles is 385 thats with extra power button off. Local driving u shouldn't expect much cause stop n go.. Take off ext power. I'm doing highway NJ to BK everyday

 

well yea ur right,, i never bought a car without its oem diagnostic tool, thats me,, others just go with a general obd scanner

but not having one at all doubles the probability of getting ripped off on every single mil or problem...

 

My car usually run 23 mpg

 

I have an '09 GS350. I do a lot of driving (around 1,000 miles/week). I've noticed its mpg can really vary on two things:
-how aggressively you hit the gas (or conversely, how you cruise at highway speeds)
-the topography of the area you're driving.

If you hit the gas a lot, pass cars a lot, the mpg will suffer. If you can keep the car cruising anywhere from 75-90mph, you can definitely see 30+ mpg. Also, if you're travelling through very hilly areas, you're gonna burn gas trying to maintain your speed over hills and inclines.

This car is a highway cruiser, and it excels at it IMO. I've taken long highway stretches where i've maintained 30-33 mpg, with a personal best of approx 420 miles per full tank. but that's when i'm not playing Hotfoot Mcgee on the highway and I just feel like cruising at a decent speed.

Ensuring you have proper inflation in your tires helps. I've noticed an increase- albeit small. but every little bit helps.