My 99 GLE went 470 miles before the fuel light came on. I figure I could get around 510 on a full tank. This was done on the interstate (78 mph) with the a/c off.

 

REALLY??????????

you think it's just "my hypothesis", well, here's a little project for you, when you fill up you gas tank record the miles at 0, then record the mileage at 3/4,1/2,1/4,E, and plot it, and see what kind of graph you get, I'll bet $ that you won't get a linear regression

 

Ok I could get 500 miles a tank if I go on the interstate and keep my damn foot off the floor. But I normally get about 200 or so around town racing all day long, I am at 230 right now and still got a little bit to go. I heard though that running the car with just a little bit of gas in it all the time is bad for the full pump, anyone know if that is true?

 

I always check my mileage every time I fill up the tank. To answer the original question, yes I have gotten 500 miles on one tank. On long road trips, I set the cruise somewhere between 74-79 and I regularly get 500 +/- 15 miles, on one tank. However, in the city I'm lucky to get much over 300 miles on a tank.

To answer the other question that came up, my fuel light comes on with about 2 gallons left in the tank. The most fuel I've ever put in the tank was 18.1 gallons with topping off, however it's not a good idea to run your gas tank that low and I'll probably never do it again.

I just came back from a road trip and I have 390 miles on 3/4 of a tank (I have 1/4 tank left).

On a side note, someone was talking about getting better mileage by not using the A/C. I have found that I actually get better mileage with the A/C on than with windows and the sunroof open. I think opening up windows and/or the sunroof hurts your aerodynamics more than it helps the efficiency of the engine. I haven't really noticed a huge difference between having the A/C on and not having it on with the widows & sunroof closed. But, I'm sure that would result in a little better mileage.

BTW, here are the stats on my car
96 SE 5-speed
73k miles
93 octane Shell or BP gas
Still using dino oil (Pennzoil), changed every 4-5k
K&N drop-in (I'm sure this doesn't help or hurt the mileage)
Tires at 32 psi (I also just put new tires on, and didn't notice an appreciable change in mileage)

 

It is appropriate to label opinion as such. If you declare something without a caveat, that is an assertion of fact.

 

It might not be that the gauge is non linear, but it could be the shape of the tank effecting the gauge as well. If the gauge were linear, but the tank got fatter as it got to the bottom, then the gauge would read somewhat conservative if it were just reading the straight level of the fuel in the tank.

Also, regardeing the 33mpg, it's funny how my dad got that as well (notice it was my dad in a '95 GLE with climate control on as well.

Some tests have shown that having the windows down and ac off vs. having the ac on and windows up is negligle in terms of gas mileage at freeway speeds. So, it depends on you whether you want to use the ac, or bake in the heat with the windows down. By openeing a window, the aerodynamics of the car are altered creating additional drag. This drag counteracts the benefits of turning off the AC compressor during cruise.

As a reminder, I just wanted to note that the MPG estimates given also depend on whether the car is a 5sp or an automatic, as the auto has a taller 4th letting the engine cruise at lower rpm's.

Also, drag on the car does not go up linearly with speed, but goes up much quicker. So going 90mph vs 45mph doesn't double the drag, but goes up 4 times or more. I read in some tests that the optimum speed for optimum gas mileage on the average was in the neighborhood of 40-45mph. However, I think that number referred to cars back in the early 80's, and cars may be more aerodynamic to the point that the speed might be slightly higher.

So if you really wanted to see what kinda mpg you could get, I guess you could cruise down highway 50 in Nevada in the winter, at night doing 45mph with the cruise control on, windows up, factory wheels and tires inflated to slightly higher than recommended tire pressure, no stereo, dry conditions. I say at night in the winter because the cooler, denser air may let the car run more efficiently. Also, by being cooler, you won't need the ac on or the windows down. By not needing to turn on the fan, you're lessening the load on the alternator. Because it's all straight on that section of 50, you won't need to turn your steering wheel much, lessening power steering pump load. By having the stereo off and no rain for no wiper blades, you're once again putting less load on the alternator. Higher tire pressures will lower rolling resistance. Factory wheels/tires as the wider the tire, the more rolling resistence you get. Finally, the dry conditions, because when it's raining, the rolling resistance goes up as your tire has to push through the water on the road.

-V

 

I disagree with you on the 2nd statement

and I'll tell you why. if I could get 250 miles to the first 1/2 a tank, then I would rationally think that I could get 500 miles to the tank, that is NOT CORRECT, the most I could get out of the tank is around 400, with 2 galons left to spare and lets say the average of 25 mi/g, so that theoretically makes my gas tank go 340, that's still 50 miles short of the ideal mileage. ==>> you THINK that you're getting good mileage in the beginning when the middle is just moving slow

 

My thoughts exactly!I didn't elaborate too much before when I mentioned AC, but vmok is totally on point.

DW

 

This statement assumes that when the fuel gages says 1/2, there is actually half a tank of gas left. The only way to tell for sure is if you fill up the tank when your reach half, and the tank should fill to full with 18.5/2=9.25 gallons of gas.

It has been my experience that the gage in any car is not that accurate, it is simply designed to give you a ballpark figure of just where you are in your tank. As the fuel level gets lower, the gages accuracy may increase. When your tank is full, it says so and we are usually not concerned about how accurate the "full" reading is, just so long as its way up there. when it's empty, we get cautious, and the gage is very good at informing us of the situation

DW

 

I think you're exactly right. At least in my Caprice, when the gauge is below 1/2, it is mighty accurate. I once filled up when the gauge showed 1/8th left. It took a little more than 20 gallons. 23-20.xx = a little less than 3. 23/8 = 2.875, or a little less than 3. I was impressed. Besides, we want it accurate down there anyway. Who cares if when it says 3/4 left, it's really 3/5, etc.

 

Okay,

I saw a lot of interesting takes, opinions, and facts about this one. I know when I'm on the road, traveling from Atlanta to Chicago, @ 1/2 tank I'm about 260(257 to be exact). I don't know if it is linear or not, I'm just know that the bottom line is the final mileage, which right now I'm averaging about 450 per tank.

K

 

wtf~!!!!!!!! i get horrible milage man..freakin yall talkin aobut 350 400 450 500 dude i get 240 if im lucky~!

 

krngimp,
Keep in mind these 450 and 500 numbers are all highway miles with the cruise on! I posted that I have gotten 500 miles on a tank numerous times, but around the city in stop and go traffic I am usually in the 250-325 mile range for one tank of gas.

Two other things to keep in mind, 1) when I get over 500 miles on a tank I am using 16.5-17 gallons before I fill up. 2) Don't underestimate the impact that using cruise has on mpg! Constant speed (even if it's at 75-80 mph) is a lot easier on the mpg than constant acceleration and deceleration.

 

Yeah I agree most of that is on the highway. In city, I'm still getting 400 miles easy in Atlanta. I'll let you know what it is in Chicago. I'm at 310 miles with a quarter of a tank left now.

Kevin

 

icic ok i'll see how it is on a roada trip or sumthing hehe

 

I feel the same way, my gas mileage BLOWS.

 

the light broke

 

i'm happy if i can get at least 415mi before i fill up. my last tank was an average of 25mpg. my best tank was 28mpg a couple tanks ago. do you think the cooler weather with less humidity has anything to do with fuel mileage? my mileage is always at its best during the warm summer months and worst on the coldest winter months.

 

Man this is an interesting thread. Although I wish the US would use metric insteads of imperial. In New Zealand most of my cars life is spent driving to the city on friday and saturday nights then cruising around the town. I Usually get maybe 500km from a tank doing this. I am happy if my car would do 10km per litre. I think the key to getting good gas milage is to not use open loop mode, ie full throttle. Doesn't open loop mode start when your over half throttle?
Another thing for good gas milage, is not how you drive but the maintenence of the car. Regular servicing, tyres aligned and inflated properly, that sort of thing.

THOUGHT
And a litre of petrol must have a huge huge amount of energy if it can move 1300kg a distance of 10km.

 

How so? I always drive at least 10 miles after the light has turned on. Am I doing something wrong here?

 

when i drove to fla i was gettin about 475. probably coulda got more but it was convenient to stop when i did.

 

When I'm talking about the AC, its a comparison between driving with the AC on, or AC off AND the windows closed, and maybe the sunroof open. Usually you can do this only when the outside temperature is lower than the temp you're comfortable with. That way, you can use Econ mode and just pull in the outside air and warm it up to what you're comfortable with. If it's 65 degrees on the highway, you can travel with the AC off and set your auto climate control to 68 in econ mode, and still have the windows closed. No AC, better feul economy.

DW

 

465 is the best I got on my trip to NOPI, Regular is about ~350/tank
Jason

 

hi everyone... i noticed someone on page 1 or 2 of this thread (forgive me i forget your name- it was so long ago, this thread is huge ) suspected that there may be a bunch of junk or deposits at the bottom of the tank, since they have 100,000 miles or more. i was wondering if anyone can confirm this - i have 113,000 miles & if it's true, is there any way (or good reason to) remove & clean out the gas tank?
sorry if it sounds like a dumb question. thanks in advance,
maury

 

I got 485 once in my 96 5spd, and I still had almost 2 gallons of gas left... I miss that car...