doritofeet

I've seen some older threads about mileage but thought i'd start a new one since everybody's car is a bit older by now. i have a 2004 GX470 and i'm getting a whopping 10.5mpg. Obviously, i didn't expect good fuel economy from the car when i bought it a couple of weeks ago BUT i was hoping for around 14mpg at least! i'm on my fourth tank and am calculating by hand. the computer says my average is 14.5mpg, yeah right! anybody have ideas about what could be dropping my fuel economy on the engine side of things? i've done everything easy, air filter, tires inflated to 40psi, drive really conservatively. BTW, none of that even made much difference. the car also has new plugs, timing belt, water pump, radiator and what looks like one new air/fuel sensor on the driver side, pre cat. the passenger side sensor looks original...

is anybody else getting mileage this bad?

LS400_96

I would start with resetting the ECU. You can remove the battery and press on the brakes a few times to discharge the residual power in the ECU and connector the battery terminals to the battery after about 5-10 mins. Start driving the car very conservatively and make the ECU relearn how you drive.

Do you have any check engine lights by any chance? Seems like most of the mx items have been performed. What type of plugs and A/F sensor (I assume oxygen sensor) did you use (OEM, aftermarket)? Is this mainly city driving?

LexRex

Stuck brake caliper pistons or misadjusted parking brake could mean dragging brakes. Do any of your wheel hubs get really hot when driving?

LexRex

And does it have stock tires on it?

265/65_17

chiph9

After one of your regular drives, look under the vehicle at the cats to see if they're red (don't touch, though! Hot! Hot!) That would indicate the engine is running really rich, and is likely caused by failing O2 sensor(s).

Also - I can recommend Fuelly.com to record your mileage. They have a mobile web-browser friendly version too.

Chip H.

doritofeet

awesome, thanks for the suggestions. i'll start banging these things out and post back with progress.

IanB2

Definitely check for a frozen caliper dragging, I get that kind of mileage in the winter with ours using the command start to pre-heat it, but you're in Florida so this isn't cold weather and idling related.

You could also change the fuel filter, PCV, and diff/TC fluids, and run synthetic motor oil if you're looking for other things that MIGHT make a difference.

new2012jee

Plus to all of this...but also may need some dealer love

ALAN553

O2 sensors? They don't necessarily have to throw a trouble code. They have an end life in regards to efficiency and they control air fuel mixture.