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Monterey drinking fuel!

Hi, on our 05 mercury monterey suddenly the mileage has gone down dramitically as per the dasboard display. The display changes within 1/2 mile how much miles to empty. This morning it was 129 miles to empty and we drove around 50 miles from work, home and it showed 24 miles to empty.
The steering was also making squeaky noise while turning, figured out fluid was low, added fluid and now the steering seems ok. Is the mileage reduction tied to this? After adding the fuel I am seeing some positive change in display but still not mile to mile.
Any idea what could be the problem? Any pointers?


You cannot rely on the dashboard display to give you an accurate mileage reading. It should be considered “Ballpark, at best.”

Having said that, a significant reduction in fuel mileage, regardless of how it’s calculated, is something to be concerned about.

I don’t think the low power steering fluid level has anything to do with the reduced mileage, but I’d want to know where the power steering fluid was going.

Mileage displays should be considered as an “average.” Don"t expect instantaneous improvement. Give it time.

You’re making a connection that isn’t there.

Reset the display and start over.

Hi mcparadise,
Thanks for the quick reply. The display comes up when you fill gas and its some average as per the handbook. When we filled up some gas over the weekend it was showing 325+ miles to empty. This morning it was around 130, and suddently by evening it was 24. We never saw this thing happening. The display when went thro the info, showed that we are averaging 19.6 miles. So certainly something is happening. I am not connecting both things but suddenly these two things came up hence the question.
I would also like to know why the steering fluid became so low. Any idea how to check any leakage? I don’t see any drops on the ground. going to keep an eye on the level for few days.
Anyway we had oil change this weekend, don’t know if any of that contributed.

I calculate fuel mileage the old fashioned way; miles driven divided by gallons consumed. I do this every time I fill up. It tells me what my fuel mileage really is.

I’ve rented vehicles lately that have an instant mileage readout. It’s fun to watch, and a challenge as you drive, to try to keep the mileage as high as possible, but I never consider the readout as “gospel.”

There are so many variables.

You can’t use the miles-to-empty figure for this. We need to know your miles per gallon, before and now.

The simplest answer, and probably the accurate one, is that your car’s fuel economy is the same as it has always been, but the display (and its associated electronics) is acting flaky.

A bit of simple record keeping over the course of several fill-ups can verify the nature of the problem. Since you have not been doing this all along nobody can compare before/after data.

For the present, all that anyone can say is “Don’t trust that display.”

If it is showing 24 miles to empty, what is the gas gauge saying, is the needle on empty? Is the low fuel light on? How many miles have you driven since you filled it?

Thanks for the replies so far. I am going to check the mileage old fashioned way, like filling the tank and checking the miles driven between each fill up (which I do for my other car). This is the first car that we have with a display so you tend to rely on that when you don’t top off during fill ups. The gas guage also shows movement and we filled up before the fuel light came up. Again this morning, drove around 7 miles and the display went down by 20! but again instead of trusting the display will check the miles between fill ups. Thanks,

I do a lot of in town/short hop driving, so when I fill up, my ‘miles to empty’ reads 297~300. Took a nice little highway drive and filled up the next time, it showed 330 miles, but then went back to normal after a few normal(for me) driving cycles.

Seven miles? You can’t tell anything in seven miles.

Is the check engine light on? If so have the codes pulled from the ECU, this will probably help you find your problem.

I have filled up the tank and going to watch the miles during next few fill ups.
This morning it was complete different story. I drove 20 miles to work and the display went down only 14. Yesterday it was complete opposite happening (7/20, etc). I am not comparing, but just posting what I am seeing. If the mileage turns out ok, i may just shut the display off! and rely on the fuel gauge, and no, the check engine light is not on, infact the system check shows everything ok. Funny thing is it shows if wiper washer fluid is low but does not show if power steering fluid is low, which was severely low!! and is more important.
Also observed that engine is slightly unrefined at lower speed (<40) and rpm climbs above 2000 (and stays around 1800) when trying to accelerate from that speed or after taking a turn. The rpm drops to less than 1400 when the car is driving at or above 45/50mph.

From the 2005 Mercury Monterey owmers manual;
Distance to empty (DTE)
Selecting this function from the
INFO menu estimates approximately
how far you can drive with the fuel
remaining in your tank under
normal driving conditions.
Remember to turn the ignition OFF
when refueling to allow this feature
to correctly detect the added fuel.
DTE is calculated using a running average fuel economy, which is based
on your recent driving history of 500 miles (800 km).

As stated this value is an estimate based on the last 500 miles. If current driving conditions consume more fuel (city driving with A/C) your driving range may be less. The fuel gauge is allways the primary method of mointoring fuel level, the DTE display is an estimate (entertainment).

Consumable fluids like washer fluid and gasoline have level sensors, while other fluids like engine oil, transmission fluid, coolant and power steering fluid most of the time do not. They require a “hands on” inspection on a regular basis.