CougarRed

The owners manual says we have a 20 gallon tank.

My computer says I am getting 17.1 mpg (100% city driving). I reset the mpg at the start of this tank. Theoretically, my range should be 335-340 miles if I maintain that mpg.

However, my range/miles to empty indicator says I have 190 miles left after driving 130 miles.

320 miles is about 1 gallon less than 335-340 miles.

Of course, the range/miles to empty indicator starts flashing with ~20 miles left to fill your tank.

My question is this:

Is "range/miles to empty" really "range/miles to ~1 gallon left"? When the range indicator starts flashing, do I really have ~2 gallons left? In other words, do they idiot proof it and "short change the range" just to prevent disaster?

It would make sense that they would. I wouldn't have a quarrel with it. Just want to know the true facts.

Thanks for your help.

Black Betty

iTrader: (60)

Yes. The distance to empty is not accurate and errs on the side of caution by quite a bit. There are at least 2+ gallons left in the tank when it reads 0 miles. I've driven 50+ miles after it reads 0 and only got about 18.XX gallons in the tank. It's only a rough guideline to when your tank will be "mostly empty".

SM_Shadowman

I've had the same experience as BB. It's as if the DTE is based on an 18 gallon tank + 2 gallon reserve once it hits 0.

Black Betty

iTrader: (60)

I've been tempted to see exactly how far it will run beyond the "---" DTE until it runs completely out of fuel and have a gas can in the trunk to refill it. I don't want to risk any potential damage to the fuel system from running it completely dry, although if I stop right away I don't think there will be any. Not willing to risk it. It would also let me discover the exact usable capacity of the fuel tank. I suspect it's not quite a full 20 gallons.

Blackjack

iTrader: (3)

Do it! I'd be interested in seeing the result.

marcelo19lp

How u get that, I fill up drive normal here in Jersey, once full computer says 280 left. I drive like 13 miles to work in the morning, mostly traffic in highway, and the rest the streets. I use AC now, but like 30% of the time. By the time its almost 0, I have put on 280 miles on tank.

CougarRed

Let me guess. When you hit INFO, and check your MPG, it says 15.6?

You're a very consistent driver. Your computer knows exactly what miles per gallon you get. So it calculates the range on something less than 20 gallons. Probably 18 if the posters above are correct.

So, when 18 gallons are gone, your range is 0 and you have driven 280 miles if you average 15.6 mpg.

When you fill up at the pump after your range hits 0, how many gallons do you normally put in your car?

SM_Shadowman

AC makes a fairly negligible difference these days. Less than 1mpg at least.

Check out the whole gas mileage thread, there seems to be a divide where some people are getting numbers like yours while others like me often get more like around 380-400+ to a tank (so 21-22 mpg) unless I've been doing an abnormally greater amount of city driving. Even though there's plenty of traffic around here, I guess it's that I mainly do highway driving, total of 25 miles each direction (50/day) for going to work.

Not really sure the reason, maybe it's mainly from shorter trips or more city driving, etc, etc. I drive fairly aggressively too, so I could probably do even better if I wanted to.

marcelo19lp

When fill up time is do, I pay for 18.2 gallons, I drove once for 320 miles with 0 reading left, So average for me is 280... So I drove 50 miles extra on 0 range, when fill up time came i put on 19.3 gallons. Wow WOW WOW how can someone get 380-400. the only way I can do that, is if I have a road trip no trafic on the parkway south drive like 70-80 mph no traffic, then the PC says 25MPG, 390-410 miles range. I drive short to work 12 miles, 40% using brakes, traffic. Then 12 miles back short trip traffic. In the end, I love the car.

SkyMG37x

Miles to Empty will dymanically change depending on your short term mileage. For example, when I fill up my tank and drive the short distance home mainly uphill, the fuel economy guage will show 15 mpg and my Miles to Empty will start dropping quicker than the 1.5 miles I drove. The next day as I drive to work on the highway the info will start adjusting and show a more accurate ~20 MPH and associated range. If you let your car sit idling for a few minutes waiting for someone you will also see the Miles to Empty number drop by quite a bit. As the tank level drops it seems to become more sensitive to these dynamic changes. Bottom line - it's conservative to prevent you running out of gas. Having said that it's spot on accurate when driving long highway trips that average 27+ MPG.

CougarRed

So I fire it up today, having driven 287 miles on this tank. The range starts out at 37 miles.

Soon, the range drops to 34 miles and all hell breaks loose. A yellow warning light comes on and the range starts flashing. Then the range starts shedding miles like they were wear metals. 34 to 27 to 23 to 16 to 9 to 5 to --- by the time I drive 13 miles and hit 300 miles on this tank.

I swear to Christ if I didn't know any better, I would have thought I blew a fuel pump!

I fill it up shortly after the 300 mark, and after topping it off all I can squeeze in the tank is 18 gallons. It holds 20 of course. Range to empty leaves 2 gallons to spare, as noted above.

When I fire it back up, the range reset to 360 miles. Which is 20 mpg if the range is calculated on 18 gallons. The computer says I'm getting 17.4 mpg. Weird.

hispeed-lowdrag

iTrader: (7)

that's not weird at all...the DTE gets less and less accurate the lower the gas level gets. On your next tank wait until it says ~40-50 miles DTE then floor it and a second later it'll say ~5 or 0 miles DTE.

it's an approximation, not an exact meter

Black Betty

iTrader: (60)

CougarRed,

Are you by chance an engineer? You analyze this stuff WAY too deeply. Post #2 explains it perfectly.

G-ThirtySe7en

The DTE is just plain daffy. Today I started the car and the DTE gave the warning light, with 81 miles range. In the 1 mile it took to drive to the gas station, the range went to 65. Filled up, and the car took 13 gallons. I mean, I had over a quarter tank left and the car is giving me warning lights! Worthless.

djshortsleeve

I just purchased a CPO 2008 g37 and have driven it for 3 tanks worth. I am reading 22 mpg eff and get about 400 miles between fill ups.

Its worth mentioning what you use for gas; i use 93.