civic question

[hi tech hillbilly]

i have a 2000 civic lx auto 4 door that i drive about 400+ miles a week (work 4 10s a week and commute 100mi a day round trip) and have noticed that the top half of the tank averages about 220-240 miles and the last half gets about 180-190 miles. has anyone had their tank out? does it taper down from top to bottom? i have been averaging between 35-40mpg driving 1mph below all posted speed limits with a/c on on the return trip in the afternoon. im also unfortunately driving on siped snow tires that are hella grippy, so i know im losing a ton of energy through tire resistance. im gonna start doing some aero mods pretty soon, need to find out an attractive looking way to fill in the fog light recesses in the front bumper and also try covering the outer lower grill opening(in bumper cover). i have access to some pretty nice sheet metal tools at work, and can get a pretty groovy discount on sheet metal so i will be covering the underside in aluminum in time as well. has anyone tried diffusers/flares in front of the wheel openings to divert air around the tires? i have been thinking about trying this out as well.. i have been thinking about ways to legally remove both side view mirrors, possibly using small 2.4ghz cameras on the outside, and 3"-4" color lcd screens inside the car. thoughts advice or opinions?

[Jay2TheRescue]

This is true of almost all vehicles. The problem isn't the tank. As a matter of fact, for the gauge to read more accurately, the tank would need to widen towards the bottom. This is due to the simple fact that your fuel tank sensor is nothing but a variable resistor. As a general rule, when a resistor is halfway, you don't get exactly 1/2 the current. Variable resistors have a "curve" that they operate on. To get one that reads exactly you would need a linear variable resistor, which is very expensive. The automakers usually favor something that averages out. You could put the slow end either at the top, or the bottom of the tank. My guess the automakers put it at the top of the tank because of perceptions that the vehicle maybe doesn't get good mileage Just because the gauge pulls off of Full within 20 miles. I often hear people brag that they can drive 100 miles before the needle dips below Full. They say nothing about the vehicle only going 100 miles between 1/4 tank and Empty.

-Jay

[R.I.D.E.]

Refill the tank at 3/4, 1/2 and 1/4 to see what actually is the true reading.

My Echo took 6.067 gallons at 1/2 tank. The tank is supposed to hold 11.9 gallons. I was at 311 miles, 51.26 MPG.

Most of the guages I have seen are fairly accurate at 1/2, then drop quickly to 1/4 then if you run it dry it will definitely take longer than from 1/2 to 1/4.

I believe this is because they do not want you to fun it dry, bad for in tank electric fuel pumps.

regards
gary

[palemelanesian]

I keep records of gallons (calculated from miles and scangauge mpg) at the marks on the gauge. My experience matches yours.

F - 1/2 = 4.9 gal
1/2 - E = 3.9 gal

(you can fit 3+ gallons above F if you are patient at the pump)