Dte (drive to empty)

I have 2006 Nissan Sentra 1.8L, 4 cylinder, auto with Special Edition package. It has a computer that gives me among other things my miles per gallon (mpg) and the miles to drive before empty (dte). But the numbers do not add up. If I calculate the mpg using the fuel warning light and the odometer mileage and compare it with calculations using the mpg and then again using the dte, all three are different with a margin of error of over 50 miles or a gallon and a half of fuel. What’s going on? Is something wrong in this car that I have bought new, or did Nissan get this wrong? Scary if my fuel warning light fails. I know my calculations are right, because the odometer cannot be wrong.

I’m sorry but this should be irrelevant. Don’t let the tank get that empty. Fill it up at 1/2 or 1/4 and you won’t run out on the highway or in traffic and the car will be much happier.

Second that, and would ask you how you know that your odometer can’t be wrong?

Not only can your odometer be wrong, one manufacturer actually had a problem with a very large number of vehicles with bad odometers a few years ago.

And, that manufacturer was…NISSAN!

That little bit of trivia aside, those who regularly attempt to drive until their gas tank is empty are not very wise, as this does nothing positive for the car and may wind up being very negative for both the car and the driver.

I have no problem if you wish to dte. That’s your business.

If you are basing calculations on the fuel warning light, or the manual’s tank capacity, you are sure to get invalid results. None of these values reflect real-world values. The computer is likely also programmed with this values, possibly to give you a safety margin.

If you wish, provide us with the actual figures that you use for calculation. We can advise you on the most realistic set of results for your purpose, which you neglected to tell us as well.

It’s possible that they’ve calculated the dte to define “empty” as having only 1-1/2 gallons left in order to protect the fuel pump. IMHO there is absolutely no reason to let it go that low anyway.

Can’t you burn up a fuel pump if you run it dry? Also, can’t you suck in the crud that falls to the bottom of the gas tank if you run it dry? Also, can’t you risk condensation and fuel line freeze if you run your tank dry in the winter? I know that humankind is curious . . . but why would you run your gas tank down to empty? To see if the computer matches your calculations? Don’t do it. Rocketman

I believe you are right on that. On a hot day running very low on gas will heat up the recirculating fuel to where it can no longer cool the fuel pump. This may not be true for all vehicles. All the reasons given above will want you to top up when the gas gage reaches 1/4 tank. If you park in a heated garage at work, but park outside at home in the winter, you have the perfect environment for condensation to form if you run the tank low.

As an added measure, I add gasline antifreeze (alcohol) to every tankful in the winter.

I don’t know how you computer mileage using the odometer and a fuel warring light. First the fuel warning light is seldom consistent from one tank to another. The only accurate way to measure mpg is by filling the tank, driving and then filling it again divide the miles by the gallons and repeat at least two more times in a row. If the numbers are close then you are likely accurate. Only as accurate as the odometer.

As noted, don’t make a habit of lighting up the low fuel light. You are working the fuel pump too hard.

Well isn’t the DTE part of the equation going to be variable because of extra fuel consumption (wide open throttle acceleration, etc) and less fuel consumption (idling) ? As someone else mentioned, “empty” might mean that the car has reached the threshold of it’s usable reserve (1.5-2 u.s. gallons). But if you’re seeing a fuel warning light, that isn’t good anyway. Seems risky to me. I heard that some cars that literally run out of gas sometimes have to be towed to the shop to be restarted after a fresh fill-up because of severe vapor lock in the fuel system.

Enjoy your driving and do it safely. Put the useless toys out of your mind. They serve little purpose and you already should know that they don’t work on any other car either.

As an added measure, I add gasline antifreeze (alcohol) to every tankful in the winter.

With most (or all) gas today containing 10% ethanol, what’s the benefit for increasing your fuel’s “dry gas” content beyond 10%?

If the pump has 5 or 10% ethanol, I don’t add it. But in my area many gas stations still sell just gas without any ethanol added.

Having a drivers license through the gas cirsis of the 70’s…I NEVER let my tank get below 1/8th full…Usually 1/4 full. During the gas crisis you never knew when you’d be able to fill up again, so I’d start looking around when it got to about 1/4 full. Usually took a couple days to find a gas station that was open and had gas.

Gas crisis of the 70’s? At least it was cheaper. I don’t know if i can handle any higher prices. But i guess at least we have supply

It may be expensive today (though inflation adjusted it’s not too bad), but these days you have no problem finding fuel. I remember having to search to find a gas station that actually had gasoline to sell. I remember pushing my car up to the pumps when it ran out waiting in line, and I could not buy the day before because there was an even/odd day rule that meant I had to wait until an odd numbered day to put gas in my car with an odd numbered license plate. If you aren’t old enough to remember it, and you parents haven’t told you about it, I know it may seem hard to believe. Seeing signs saying, “NO GAS” at gas stations was common for a few months in the 1970s.

Gas crisis of the 70’s? At least it was cheaper

Cheap is relative. I bought a brand new car back then for around $3000. Gas was perhaps $0.50/gal IIRC. The same car today would be in the neighborhood of $18k and gas is $3.00/gal. So all in all, I think things haven’t changed that much, relatively speaking at today’s gas prices. Up until recently, it hasn’t kept pace with other other commodities and people have grown used to the lower prices…

No it wasn’t!!..Not when you count in inflation…Plus the fact the gas prices TRIPPLED in just a few months. It was a major strain on me. Just back from Nam…poor college student, I didn’t have a lot of money to buy gas when it was 35cents…let alone 90cents 2 months later.