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Old 06-30-2010, 01:10 AM   #9 (permalink)
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Nissan Cube - '10 Nissan Cube Base
90 day: 33.35 mpg (US)

The BRG - '91 Mazda Miata SE
90 day: 35.9 mpg (US)
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Originally Posted by RobertSmalls View Post
I'm pretty sure it's not broken. The engineer's intent is for the gauge to manage your perceptions and behavior. The top half of the gauge's swing might represent 2/3 of the tank. Users who fill when the tank gets to half may think their car is very efficient to get 250mi on half a tank.

The gauge's behavior at the bottom is more important for managing user behavior. I never found the bottom of my Subaru's fuel tank, but the needle would move past E for another 3/16ths of a tank indicated without running dry. That gauge was very non-linear throughout its entire range.

Similarly, my Insight's (and cell phone's) battery SoC gauge lies notoriously to manage my perceptions. As long as its lies are consistent, you learn to live with it.

And yes, your car's ability to measure its fuel level is somewhat limited. It usually relies on a float attached to the fuel pump: fuel level at a single point in the tank, and not always the center of the tank, either.
I realize all of that and am not questioning that. As far as that is concerned, the gauge does in fact move fairly linear. The thing I'm complaining about is the gauge dropping one to two bars just from being parked for a few hours on level ground. It only does this in the first 3 bars of the gauge. After that, it's fine, but like right now it's reading that the tank is down almost by a 0.25 at less than 60 miles which I know for a fact is not accurate at all. If the tank was truly that low, I'd be closer to 85-90 miles.

Example... When I got home last night, I had exactly 50 miles on this tank and the gas gauge had dropped ONLY one bar from full which is normal. I got up this morning to take my girlfriend to work, go out and start up the car only to find that the gauge dropped 2 more bars for absolutely no reason whatsoever. And yes, I was parked on level ground as I always am.

The fuel sending unit has been replaced twice and the same exact results every time. Also, the dealership pulled all three units (they saved the first two), put them all on the bench and measured them throughout their entire operating range. All three measured the same! Who knows... Apparently Nissan doesn't.

Anyway, I didn't mean to take my own thread off topic. LOL
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