Reserve indicator inaccuracy?

[rollingtones]

The smart fuel tank, sending unit and gauge have a hidden safety feature. After your gauge reads 0.0 miles to empty, you still have .1 to .2 gallons in the bottom of the tank.

This is a safety feature in that running out of fuel on a roadway can be very dangerous, depending on the circumstances. smart is not the only carmaker to do this.

[nmcl714]

Originally Posted by Tinman2000

I'm beginning to think my gauge is inaccurate and have been filling every 250 miles or so. I recently filled up at the beginning of a trip to PA and the gauge read full until I reached 108 miles, mixed driving.

The same thing happen to me twice on a trip ti OH this past weekend. Filled up and gaugue stay on full the first time to 101.2 miles the second time it went to 149.8 miles befor it went down a bar.


FMF Doc

[unicycle]

Remember, I was asking about RESERVE fuel info. Many of us have experienced what tinman and nmcl mentioned, namely that the first little bar doesn't give accurate information of what you've just used up. I've had readings varying from 90 miles down to 70 miles.

But the more important point is that if you think you have a gallon left in the reserve and it turns out you have a lot less, you could be in serious trouble. Alternatively, if you fill up well before you have to, you might find that annoying (tho at least you won't run out of gas).

So remember, we're trying to get to the bottom of these puzzle (and our fuel tanks!): How much is truly in reserve, and how much fuel do our putt-putts really carry? Do they really only have 8.7, or might it be closer to 9.0? That sort of thing...

[rawlus®]

i think the problem is in thinking about it as a reserve. it's not - there's only one gas tank. it's just that at a certain level the reading of the tank's capacity changes to a finer measurement. every car i've owned has "seemed" to hold more than the gauge tells me. like the rare time you're running "on fumes" with the gauge reading below the E and you're sure you're gonna run out any moment but you make it just in time to a gas station afterall. there was even a Seinfeld episode based on this phenomena.

my suggestion would be not to get too caught up in what the gauge reads and the deeper meanings behind it. life is too short. the gas gauge on my 97 jeep wrangler has been broken for years - sometimes it'll read mostly accurately, other times it will read empty (even when the tank is full) - the thing is tho - the way the fuel gauge sender works it won't ever read MORE than what's in the tank, only possibly less than what's in the tank.

so i wouldn't draw any assumptions that the gauge in the smart would overreport the fuel you have remaining and cause you to get stranded with bars still visible on the display - probably the opposite that when it runs out, there may be a tad more in there due to incline, baffles and a designed-in fudge factor to ensure those that don't even think about refueling until it reads empty don't find themselves on the side of the road without gas in the tank.

since gasoline prices are soaring on a daily basis - filling up when only half full rather than waiting all week to fill up when nearly empty should save you a few pennies by buying a half-tank at a cheaper price than a full tank for more money.

[artificial]

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[rawlus®]

how am i driving further? fill now or fill later, the same amt of gas is used over the same period of time. i'm just filling up and driving to half full again instead of being half-full and driving to near-empty.