What is "True" Petrol Empty?
 

I now live in NC. Gas stations are much more common in CA than they are here. I was on an excursion yesterday/evening. My "50 Miles to Empty" warning came on. My GPS said home was 39 miles away. Wasn't too concerned.

GPS routed me to a dirt road. :-( I don't do DIRT roads. Changed course. So, here it is DARK in NC and "miles to empty" kept updating me, and gas stations didn't appear on the horizon. Could have/should have checked the GPS for nearest gas stations, didn't.

Long story short, I filled up when the "miles to empty" said I had about 12 to 14 miles left, don't recall exactly. It took 15.44 gallons.

Anyone found out what TRUE EMPTY is?

I could have checked the "Gallons Used" as a double check, 99% of the time when I compare reciept to that when filling the two readings are within a couple of tenths of a gallon. This time it was a gallon off, and would have given me false hope if I had looked at it. Must have omitted to reset it a the last fill up. Also, my average MPG for ALL driving in NC for 2008 is 19.97

1) Don't trust the onboard computer. It's historically inaccurate.
2) Don't let yourself get that low, knowing:
a) "Gas stations are much more common in CA than they are here"
b) You don't want to suck the garbage out of the bottom of the tank

We have a 16 gallon fuel capacity. I would think when the tank is empty, that would be "True Empty"... (ya' think?)

Not going to disagree with you. Should have filled up earlier. Didn't really think the excursion would chalk out at some 120 miles, I was thinking 80 - 90 miles when I left. Didn't really plan for the route I ended taking on the way back, I had figured there would be a station on the way.

However, "True Empty" - when the car runs dry because it can't reach that last portion still in the tank. On a GT that could be with a 1/2 gallon remaining, but I don't know.

I've heard for years the story about garbage in the bottom of the tank. My last car was a BMW, 29 years old, 269,000 miles, when I sold it. You could look into the gas tank by pulling the back seat bottom and doing a quick operation to pull the fuel pump and filter. EVERY time I did that, the tank look brand new inside. My '89 GMC PU with 172k on the meter a few months ago needed a new fuel pump. Its in the tank. Mechanic told me the tank was perfectly clean inside.

I only fill at good gas stations, but, I wouldn't fill up if the delivery truck was making a delivery unless I had to do so.

when the car says "0 miles to empty" you have about 1 gallon left

First you dont have to worry about sucking dirt up into the pump if you have some at the bottom of your tank. All these cars with electric fuel pumps have pre-filters on the pump. Usually called "socks". Second running a on an empty tank can severely shorten fuel pump life. Not only does the gas act as a lubricant for the fuel pump but it also keeps the pump cool during operation. We wouldnt run our cars without oil or coolant so why would you want to risk it just buy squeeking out every last drop of the tank. If you own a s197 your not broke usually, keep that tank at 1/4 or more at all times.

I also think the computer may not be perfectly accurate. I've had it tell me 25 miles to empty but when I went to fill up it would only take 13.5 gallons. If it's a 16 gallon tank that would mean there should've been 2.5 gallons left which would provide for significantly more than 25 miles of travel.

Something isn't right with that picture.

weird... i've gotten down to "1 mile left" and when I filled up it took less than 15. I thought that we had a 15 gallon capacity.

16 gallons per the manual. I hand calculate at every fill-up and the # of gallons used per the gas pump is typically about 1 gallon or more than the computer and I've heard that from a lot of others. Use the on-board info for just that, info.

I would suspect the gauge is the best indicator for actual fuel level.

It's kind of scary the way it alerts you. At around 7 miles to empty you get a beeping noise and a flashing light on the dash along with what the computer read out tells you. What I noticed about the whole thing is after you fill up you usually get a message saying 326 miles till empty or whatever it is. When I got down to near 0 once my miles till empty after filling up were somewhere at least 30-40 miles higher then usual. That being said I deffently wouldn't trust the computer to get you an acurrate reading since going really low seemed to bug mine out.