Miles to empty dropping fast?

[Roscop]

Hello everyone, I'm still on my first tank of gas, for the first quarter tank my mpg was increasing, and the miles to empty obviously were as well. I'm holding steady near the 45mpg mark, but my miles to empty are dropping rapidly, I'm loosing about 2 miles to empty, per every mile I drive. Anyone have an idea of what would cause this?

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[mav_kev]

 

[AutobahnSHO]

The computer is GUESSING based on your driving style and how much fuel is left.

If the amount of gas being used changes, so will the GUESS.

 

[kpomeraning]

As an example, if I'm driving around town my hybrid miles show a pretty sweet miles until empty... but when I do some driving at 70mph on the highway, it'll drop pretty significantly. Around town I'm getting 45mpg, but 70-75mph gets me around 34-36mpg.

 

[Old Man]

Don't worry about it, all those numbers are estimates.

 

[Roscop]

Thanks for the replies, I understand the computer is trying to figure it out, but it seems like it suddenly changed how it was working from before, and my driving style is pretty consistent, I'm driving the same roads, it literally lost 11 miles in a 3 mile trip of level, 35mph driving, showing 44.8 mpg on my last trip, it's gone from 400 miles to empty to 330 miles to empty in 25 miles of driving while averaging over 44 mpg

 

[JBryant]

Every vehicle I have ever owned drops rapidly once it gets down to around 50 miles left. It may get you XXX miles on the first quarter, but will do YYY miles on the last quarter. The nature of the beast. A few years ago, I quit dealing with that problem. When I get between a quarter and a half tank, I just fill it up and do not have to worry about it.

 

[Roscop]

Every vehicle I have ever owned drops rapidly once it gets down to around 50 miles left. It may get you XXX miles on the first quarter, but will do YYY miles on the last quarter. The nature of the beast. A few years ago, I quit dealing with that problem. When I get between a quarter and a half tank, I just fill it up and do not have to worry about it.

I'm not too worried about it yet, I'll go through a few tanks and see what I'm averaging, I'm just a little concerned because it changed so fast, I'm not sure if something happened, I'll keep an eye on it, I was checking to see if this has happened to anyone else.

 

[SkeeterB]

I usually don't let it get below 50 miles to empty. On highway road trips I fill at 100 miles to go. Can't see waiting to zero as not real sure I will get that far.

 

[NeilsTruck]

Most modern vehicles have the fuel pump in the gas tank and use the fuel to lubricate the pump so I rarely allow the tank to get below 1/4

 

[mielelaw]

I do not really look at the computer, it is just a guide. I have always calculated mpg by setting trip meter to zero when I fill up and then next time I fill up, divide number of miles by number of gallons and that is the most accurate mpg reading.
I do not have the hybrid so the computer is usually telling me mid-twenties. Do not have the mav that long so I have not even tried to use the formula yet. Actually happy with the computer number since my F250 that my wife uses to pull her horse trailer gets around 12 mpg on a good day.

 

[Roscop]

I do not really look at the computer, it is just a guide. I have always calculated mpg by setting trip meter to zero when I fill up and then next time I fill up, divide number of miles by number of gallons and that is the most accurate mpg reading.
I do not have the hybrid so the computer is usually telling me mid-twenties. Do not have the mav that long so I have not even tried to use the formula yet. Actually happy with the computer number since my F250 that my wife uses to pull her horse trailer gets around 12 mpg on a good day.

I'm averaging 44+mpg, I'm extremely happy about that, my F250 is only getting 8 mpg, the Maverick is amazing!

 

[CajunMick]

Probably the shape of your tank?
I noticed the gauge itself falls fast after a fill up. Then takes longer time for movement, as tank shape holds fuel in that 3/4 to 1/4 range, big volume. Once hits 1/4, then tends to fall faster. Like emptying a coke bottle upside down, when fluid hits the bottle neck, goes faster.

 

[billbillw]

Probably the shape of your tank?
I noticed the gauge itself falls fast after a fill up. Then takes longer time for movement, as tank shape holds fuel in that 3/4 to 1/4 range, big volume. Once hits 1/4, then tends to fall faster. Like emptying a coke bottle upside down, when fluid hits the bottle neck, goes faster.

The gauge should be calibrated to the volume of the tank and not to a linear drop of fluid height. That said, almost every vehicle I've owned takes forever to drop from full to 3/4, then it's faster through the remaining range. The exception was my Touareg, which would start dropping from full within 20 miles of a fill-up and it was a consistent drop.

 

[Bigfoot7262]

Most modern vehicles have the fuel pump in the gas tank and use the fuel to lubricate the pump so I rarely allow the tank to get below 1/4

Same, cars have had fuel pumps in the tank for a long time and running down to the last gallon or two will put more heat on the pump.

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