RobertC, if you are spilling ANY fuel, you are doing it wrong, and today’s vapor recovery systems minimize vapor losses.
derekvf, it is pretty easy to find a gas station on your planned route without making a special trip to the gas station and without idling in a parking lot. Also, starting a modern fuel injected engine uses very little fuel, especially when the engine is already at operating temperature. If I was driving around in my old 1969 Dodge Dart, you would have a point, but my current car is considerably newer.
I have to disagree guys. As it has been stated in the posts above (or below) The more gas you are hauling, the mileage HAS to be worse. Probably not much, but it really does have to make some difference. Aside from that, my personal experience is quite the contrary. I’ve been driving a '96 VW Jetta for the last ten years, and my gas gauge operates very differently. Firstly, it takes a good 20-30 miles for the gauge to even move from the topped out position after a fill up. After that, it makes a steady decline until the last quarter tank, which I can seemingly drive on forever. I do have a habit of driving on fumes, much to the worry of my missus. I’ve driven 50 highway miles with the gas light on. I assume the tank is 14 gallons, but driving like I do, I’ve never put more than 13.75 gallons in the tank. I really love that last quarter of a tank!
You get better fuel mileage when the tank is closer to empty.
Now I’ve seen and own cars that gauge goes down faster on the bottom half than the top and tank where the first half goes down faster than the last. It depends on the shape of the tank and where the float is located in that tank.
It also depends on how “full” that tank is, a lot of people top off their tank so a gallon or two is added to the tank after it reads full. So they are going father on the top half
I don’t think your giving Jason enough credit. I’m sure he knew what Tom & Ray meant by their answer. His wife THOUGHT the car got better mileage with a full tank because the gauge moved slower on the top half. Remember Jason ALSO asked about a womans mind, and by the way they answered his question, it gave insight into WHY she would think it was getting better mileage.
What a great discussion. So many good thoughts. What about the fact that you have to make twice as many stops to get gas? That will certainly affect gas mileage.
My example is that with less mass (as fuel burns off), you get better mileage. Lap times are relative to how much mass the engine (same HP at start and end) has to accelerate after every corner. Admittedly it is a little extreme, as you start with about 52 gallons of fuel and optimistically end on vapors. But total mass does matter.
As to 100 or so pounds being insignificant - that depends more on the type of driving (stop/start vs. steady speed) and terrain (Kansas flat vs. Rocky Mountain pass). Pushing 100 pounds continuously in a shopping cart on a flat surface is easy. Pushing it up a 14% grade (or continuously stopping and starting it) is not.
As a percentage of gas mileage, it also depends on how massive the vehicle is. For a Ford Excursion, 100 pounds vs 7100 pounds (although it has a much larger tank) is only 1.4%. In something light like a Smart Car, 100 pounds vs 1600 pounds is 6.25% (very noticeable).
If you are on a long trip, yes stopping for fuel uses more fuel than just driving past the exit. However, would you please explain to me how stopping for gas affects fuel economy if you stop at a particular corner gas station which is already on your route for your everyday commute?
The only problem I had is that Jason left thinking his wife was right! If you listen to the segment, he says a couple of times that he was glad to know his wife was right…again!!! I hope you see this and the responses Jason. We men are almost NEVER right!!! We need to let the world (and more importantly our wives) know when we actully stumble into doing or saying something right.
Nothing. 5.5 is half of 11 and you’re going to have some fuel that is “unusable.” We’ll go with the benefit of the doubt that .9 is not usable. I hope you tipped the poor soul who had to fuel you.
No, I sold it to my neighbor not long after I bought my Mazda. He was pretty impressed when I handed him the stack of papers from all my oil changes and recent muffler and brake work. My mom couldn’t understand why I done the brake work since I was selling it off anyways, and I told her I couldn’t let the guy buy it knowing the brakes weren’t in that good of shape; especially since they found out the passenger side front caliper was pretty much trashed.
Thankfully I don’t drive that much, so fuel price isn’t as important to me as it is for others.
That’s true; I only carry necessary stuff in the trunk. With the winters we have here, keeping the tank at least half full is recommended to reduce condensation and allow for being stranded. That extra 1/4 of a mile per gallon takes a backseat to safety and common sense.
Actually, it is likely that if you keep the car’s tank close to empty it would consume less fuel, especially if the car was starting and stopping often. The reason is that the additional weight of a full tank requires more energy and therefore more fuel for acceleration.
I have heard that if the person lives in a very hot place, then the answer could be different as on some older cars the fuel could evaporate and escape from the tank. If the tank has more fuel, it would take longer to heat the fuel and therefore would lose less by way of evaporation. In general though, having lived in hot places, this is rare.
I think for the purpose of this discussion, the minute differences in mileage between a full tank and an empty one are negligible. Therefore, as Tom and Ray correctly stated, the mileage is basically the same.
They also then explained why the gauge doesn’t begin to drop right away, giving the appearance of better mileage on the top half of the tank.
BUT…then they told Jason that his wife was right!!!
Given the above assumptions, she is NOT right! She only PERCEIVES that the mileage is better, when in fact, that is not the case.
So I would agree that the answer given by the Boys was incomplete, and should be clarified on a future program.
My car does the exact same thing (97 Grand Am GT) - but to an extreme. However, I have heard that dipping below the 1/4 point on the gas gauge can actually hurt the engine (and may not give as great MPG) because of the sediment that is in the tank. The sediment only gets sucked into the engine if you let the levels get low enough. Not sure it’s totally related…
If you inspect the location and operation of the fuel tank sender it might be evident why the gauge is inaccurate. The rheostat is operated by a swinging arm that begins at approximately level and perpendicular to the center of the sweep and as the fuel level drops the lever swings downward nearing the vertical position. The gauge would be somewhat accurate if the sender were centered in that cylindrical fuel tank on the truck in another on air problem.
Jason’s wife is dead wrong but it’s likely as in the case of many women she will never accept that premise. Guess that comment makes me a sexist pig but on average far more women than men will argue a point about something like this even when their knowledge of anything attached to a car is far less than zero.
“Jason’s wife is dead wrong but it’s likely as in the case of many women she will never accept that premise. Guess that comment makes me a sexist pig…”
Everything you wrote is true, except you misused the word “premise.”