Gas gauge

[Buzzardbob]

When my gas gauge gets to half it drops precipitously; so fast that I have sropped for gas for fear of running out. Yet I have been getting 31-34 mpg for the 3 or 4 times I have measured. Does the car start using more gas when the tank is less than half? I have never re-filled when it has been below the half mark. Any thoughts?

[arco]

I'm sure the car doesn't use more gas once the gauge gets below the 1/2 mark. My Versa drops off pretty quickly during the last 1/2 tank too. But so did my old Civic, and practically ever other car I've driven (quite a few).

If I had to guess, maybe it's because of the shape of the gas tank?... or the way the float mechanism operates inside the tank? I'm no physics expert, but I'd assume the fuel gauge is most accurate when the tank is full.

[TweeKeer]

it has to do with the way the float mechanism is designed and the gas tank is shaped. I notice that the gas gauge goes really slowly after the 1/4 tank mark.

More expensive cars have sensors in them so that the gas gauge drops equally, but as can be expected, it's just an expensive add-on.

[KimberKenobi]

My 'Kik was five on one side of the 1/2 mark and 3 on the other and always moved very even (you could divide out the gallons on the gage and all the spaces were even) however, I too noticed the drop rate on the Versa's gage and am glad to read the responses and see that it's just the way the sensor is made... phew.

[motoguy128]

More expensive cars have sensors in them so that the gas gauge drops equally, but as can be expected, it's just an expensive add-on.

That's funny because my '91 Toyota Tercel with a <$7000 MSRP was '03 Corolla with <$13,000MSRP, and Honda Accord were all pretty much spot on. I think Nissan just stuck a very cheap unit in there.

Oh well, I]ll just treat it like my motorcycles which don't have a fuel gauge and go by miles. 250-300 miles and I'd be looking for gas.

[achr]

As someone mentioned, MOST gas gauges are calibrated such that the needle doesn't move for awhile after fillup. This is INTENTIONAL as customers THINK they are getting better mileage when the needle moves slowly. On one of the Cadillac introductions (the STS I believe), GM used a "Properly" calibrated fuel gauge in the car. Complaints abounded that the car got LOUSY mileage because the gauge started dropping almost immediately after fillup. The next year, they replaced the gauge with the same style used in other GM cars and the lousy fuel mileage complaints ceased.

I'm ALWAYS amazed at the number of people who really have NO idea what the actual fuel economy of their vehicle is. Many times I hear, "Oh I can drive for a week and a half on a fill-up." Well duh! How far did you actually go and how many gallons did it take to refill?

[tractor07v]

Most vehicles I have driven seem to go faster after half a take even our tractors do that and they digital read outs for the fuel level(but still use a float style sensor), but also on my V I noticed that at about 1/4 or 1/8th a tank it kinda sits there for a long time and and I even drove it with the needle below the E mark and still had over a gallon left in the tank, but from experience the best way to know how much farther you can travel is to learn on average how miles you get per tank and when you near that mark get more gas, which is basically what motoguy128 said. But still I like filling up and putting in only bout 11 or 12 gallons as apposed to my truck which was 23 or 24 gallons and going the same distance