YACT: Irratic gas mileage???

[alexjohnson16]

Drive a 95 Mazda Protege...

Curious to my gas mileage...

For the first half tank, it gets 200 miles... The second half goes down in less than 110 miles each time...

Is this normal? I'm driving the same way both halves but... Just curious to if there's a reason for it or if my car is just messed up...

 

[Heisenberg]

It's probably because the halfway mark on the gauge isn't really halfway. Most likely closer to 2/3. The rumor is that car companies do that so it feels like the tank stays above half and you think you're getting good mileage. I've noticed it happens on both my cars (they're GM though).

 

[kami333]

Yes, the gas readout is never completely accurate.

 

[mugs]

My old car was the same way, the percentages on the gas guage aren't nearly accurate. I'd get 90 miles before the needle went from the pin to the full line.

 

[AgaBoogaBoo]

There may be some reserve below the bottom line or something removed from what would be the bottom half on the readout

 

[Pepsi90919]

i know the gauge on my mom's 88 BMW has the lines closer together near the empty mark.

 

[mobobuff]

Yeah mine does that too, and what's worse mine also swings 40 degrees towards F when I accelerate and 40 degrees towards E when I brake. Stupid inertia.

 

[Eli]

It has nothing to do with your actual gas milage.

It is because your fuel gauge isn't linear. I don't know of any cars that have a linear fuel gauge.

The correct way to calculate gas milage is to hit your trip button each time and make note of how many gallons you put in.

(miles driven) / (gallons) = mpg

 

[jagec]

Originally posted by: Eli
It has nothing to do with your actual gas milage.

It is because your fuel gauge isn't linear. I don't know of any cars that have a linear fuel gauge.

The correct way to calculate gas milage is to hit your trip button each time and make note of how many gallons you put in.

(miles driven) / (gallons) = mpg

Exactly. I do this every time, just out of force of habit. Who trusts the fuel gauge?

 

[Eli]

Originally posted by: jagec

Originally posted by: Eli
It has nothing to do with your actual gas milage.

It is because your fuel gauge isn't linear. I don't know of any cars that have a linear fuel gauge.

The correct way to calculate gas milage is to hit your trip button each time and make note of how many gallons you put in.

(miles driven) / (gallons) = mpg

Exactly. I do this every time, just out of force of habit. Who trusts the fuel gauge?

Same. I've always considered the fuel gauge more of an idiot light than anything. It just tells you when you need to fill up.

I'd bet there are some luxury cars, or cars of the past that have had accurate fuel gauges.. but it just must not be worth it or something.

At least most modern cars are pretty conservative. When you're on the E, you usually still have enough gas for 20 - 50 miles left..

My truck runs out as soon as the leading edge of the needle touches the edge of the E line. Of course, once you know this you compensate, but .. yeah.

 

[imported_Phil]

My old Citroen AX has a strange fuel guage- it doesn't budge from Full for the first 50-75 miles or so, then drops normally. Once it hits halfway, it drops like a stone (sigh). Also, it's not affected by going up and down hills, only when you turn corners. I guess the sensor is on the side of the tank rather than the front or back.

However, the 2004 Renault Scenic that I'm driving now has digital readouts, and they're amazingly reliable- miles left until empty, average MPG, etc etc. Very useful.

 

[Ketteringo]

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