I have a 99 elantra. When i fill my gas tank, the gas needle never reaches the full mark. It stays on 3/4. This has been going on for a long long time and it is gradually getting worse as far as mileage. I don't remember how much mileage I actually get BC it has been so long since my gauge has worked correctly. The whole motor was rebuilt the beginning of this year and the sending unit was also replaced. When my gauge hits empty, I've driven 176 miles. I filled up last night and it held 8.4 gallons. It has a 14 gallon tank. How can I fix this? Did I buy a bad sending unit, is it fuel pump, the gauge itself?

SOURCE: 97 honda civic wont start.

If the car has over 100,000 miles on it, you may need to replace the distributer. I don't think the bad gas caused this issue I think it may just be a coincdence. But if you already changed the plugs, wires, distributor cap, and rotor, I would definetly check the distributor.

SOURCE: gas mileage

Whenever I use the heater, my gas mileage goes to sh*t . If you've been using the heater all the while, and suddenly this happens, you may have a clogged air filtre or not be firing on all cylinders and may require repair. Check your filtre first, but for cylinders, a good indication is your spark plugs - if they're wet, coated, or corroded, this may be part of the problem. KIA will charge you a lot to do this, and if everything is fine, you could be out almost $800. See my thread on spark plug replacement.

Another problem that may effect your consumption is your timing belt. Check how many miles or KMs you have and see how close to servicing you are. If you are within 3000mi or 5000KM of scheduled maintenance, get it done. It cost me $640cad. I would not suggest doing this yourself.

Best of luck.

SOURCE: poor gas mileage average 13.6 miles per gallon

what kind of car is it and how many cylinders?

SOURCE: POOR GAS MILEAGE

Have you changed the fuel filter? I know it sounds weird but a plugged filter will make a truck use more gas. The computer tries to compensate for less fuel by commanding the injectors to open longer. Also a plugged filter will cause excess back pressure on the fuel pump making it loud.. Good Luck.

SOURCE: I have a 1997 ford f-250 4x4 and its lousy on gas

You could fill the tires with Nitrogen but it will cost about $15 a tire. You will gain 1.5 - 2 miles more a gallon. Big trucks were made for pulling and hualing only. If your looking at gas mileage then you need a focus.