yaro1

Imagine this:
My GX 470 loaded with enough clothes for 4 people for 10 days, all of the shoes, toiletries, pillows, and an airbed. Then add on a giant, terribly non-aerodynamic, roof rack filled with 2 Cases of water and two cases of Iced Green Tea, beach chairs, and a cooler filled with foodstuffs. Next, stuff four people in the truck. Finally, travel at 85 MPH down the Garden State Parkway (It was 2:00 AM... Deserted Road) and you have the combination for 11-13 Average MPG !

Normal highway MPG for me is between 19 and 21 MPG.

It amazes me how weight and aerodynamics kill gas mileage so badly.

Have you ever measured such poor has mileage? What do you average on highway?

(By the way: I went to Wildwood Crest, NJ (by Cape May))

CVsIS250

My onboard usually says about 18.9 mpg b/c i drive alot of highway to and from work during the week. From what I have actually calculated it is around 17.5. Anyhoo, I had my GX loaded down like yours without the roof mounted stuff. I had 3 suitcases 3 sets of golf clubs and 4 adults in her and she did about the same up and down the mountains of WV on my way to NC. I would be that your problem was the stupid roof container.

CV

llcc1975

Yaro - do you mind telling me what type of rooftop carrier you have (i.e Yakima, Thule, other)? I'm considering getting one of these because we "downsized" from a Suburban to a GX recently and are going on a roadtrip soon and I don't know where to stick all of the stuff (have little ones so lots of gear). The Yakima carriers I've been researching look about as aerodynamic as you can get but of course I also realize I'm adding a big box on top of an already boxy vehicle. I don't even get 19 - 21 as it is today on the highway (avg. about 17) so if these rooftop carriers kill mileage that badly, maybe I'll just learn to jam things in better. Thanks.

EyeKutr

iTrader: (5)

i think weight is not nearly a big factor as the speed at which you cruise, the aerodynamics of a tall SUV make a huge difference in speed....doing 65, i get 20-22 and doing 80ish i get 16-18 and any faster i usually dont maintain long enough to know.....

loflin

The effect on mpg of the drag coefficent (which you also greatly increased) goes up by more or less by the square of the velocity increase. In other words big and bigger hit as you increase speed.

Just going 85 without the windblock on the top would have had a pretty good effect on our boxy GX compared to 65.

Next time, buy the water and tea at the destination, instead of hauling it.

RC1818

just curious.....how exactly are u guys calculating ur MPG average?? whenever i fill-up my tank i always reset my B trip monitor and i seem to rarely surpass 230 miles before i have to plug her in again....although i use regular gas only (87octane) and do mix of city & hw driving....so im averaging roughly no more than 11-13 MPG as oppose to all u guys, should i which to a higher octane or tell me im doing something wrong?? ive honestly never surpassed 300+ miles ever on a full tank of gas...thx!

CVsIS250

While your GX does not, "need," premium, it seems to last longer/fill-up. I do a mix of both hway and city driving too. The trip computer with premium says 18.#. My calculations are a little lower though. Try using premium and see what happens.

CV

The G Man

I am sure those 305 tires and the EuroTech Bars doesn't help as far as gas mileage. I went back and forth with regular and premium and I calculated less than 0.5 MPG difference, so you can say that there is really no difference.

RC1818

not to repeat myself..... u guys didnt really answer my question, personally i use the B odometer as a gauge to see exactly how many miles i get to a full tank of gas then i just divide by 20 so i average out to say 11-13 MPG....i personally dont think the onboard computer (next to clock) MPG/trip average is accurate so this is why i use my method......so according to u guys with the 15+ MPG averages, are u telling me ur getting over 300+ miles each tank all the time?? btw, reason why i dont trust the computer is cuz one time when the gas light came on in the middle of east bubblefuk i needed to refill sooo desparately cuz the range indicated 0 miles left i musta drove for anutha 4 miles & almost peed before i saw the next gas stop!??!?!!?

CVsIS250

yes, i am telling you that i get 300+, normally 330 or so/tank with premium fuel and a mix of highway and city driving.
CV

RC1818

kool....next fill-up will def be PREMIUM!! much thx...

CVsIS250

it may take a few fill-ups to reach a higher mpg. you will still have residual regular in the tank for a while.

CV

seanyepez

The gasoline will mix and bring the octane number very close to what "premium" gas is if you fill up when the light comes on (only a couple gallons remaining).

http://www.motorsportsracingfuels.co...alculator.html

The real reason you won't notice a difference immediately is the fact that the ECU will need to adjust to the higher octane and advance ignition timing. It will do this over the course of a single tank, but to speed up the process, you could cut power to "reset" the ECU (either by pulling a fuse or disconnecting the battery, not sure what the best method is on the GX). This is a trick I used to use on another car to get the car to reset its learning when I filled up with 100 octane racing fuel. I would remove the battery's positive connector and hold the brake pedal down for a few seconds.

llcc1975

I have not had my GX for all that long (only enough for 3 tankfulls). I have not gotten close to 300 on a "tank" but this statement needs to be clarified. With a mix of highway/street driving (about 1/2 and 1/2), we have only gotten about 250 miles before the low fuel light comes on (and the gas gauge is on "E"). When I go to fill it up however, I can't really squeeze in more than 18 gallons (and believe me I am trying to 'top it off' as much as I can).

According to my documentation, this truck has a 23+ gallon tank. So I'll make a presumption that I have about 5 gallons in reserve even on "E." Thus, my mileage is averaging about 13.89 mpg in mixed driving. This despite the fact that my onboard trip computer states that I'm getting about 14.6 mpg. Not knowing the margin of error for the trip computer, I'd say that it is relatively accurate.

I stated above that I'm getting about 17 mpg but that was for highway driving and I am going completely by the trip computer for this figure. I am using 87 octane and I also have a Yakima rooftop rack on top of the factory racks.

When you guys are saying that you are getting b/w 300-330 mpg using 91 octane, is that from top off to the low fuel light coming on or are you pushing it way past that point? Be interested in knowing. Thanks.

SilverLady

RC - why are you dividing by 20? You need to divide by how much gas you actually put in the GX each time. 20 would be the actual worst case - you will rarely be putting in that much gas unless you go to empty!

I recently reset my mileage computer for a couple of 400+ mile round trips I took to upstate NY. The driving was mostly New Jersey Turnpike/Garden State Parkway/New York State Thruway. Other than a few rough traffic spots I was going about 65-75 (EasyPass helps too!). I was pleased that the mileage was over 19mpg. My usual around town driving runs around 15-16mpg. If the computer is to be believed, it is right on the EPA estimate.

Of course this was with Premium (93 octane), one to three people in the vehicle, a few suitcases which added at most a couple hundred pounds, and no roof rack. AC was on most of the time.

The roof rack can be a killer for the aerodynamics. That was some expensive water and iced tea!