Well, it was a while since I had it that bad.
Just stopped to fuel up, gas was not very low, a bit on top of where red mark starts, almost a qt tank left. So I pour in 10gal and stop at $40, drive off and look at gas gauge I see needle is exactle between 4/4 and 2/4 marks. So I guess I got may be 6 or 7 gallons while paid for 10. Nice.

 

Maybe I can illuminate. Half way between 4/4 and 2/4 would be 3/4. In my car (GTS) the the red mark is approximately 2 gallons remaining and you were slightly above that (the red mark is 1/8 of a tank). Assume a 16.5 gallon tank. You have ~2 gallons and put in 10 gallons = ~12 gallons which is approximately 3/4 of 16.5. Gas pumps are pretty regulated, sealed and tested and there is a hefty fine if a station is caught tampering with them.

 

not only the above, but you act like the gauge is perfect, which its far from.

 

You should come to Ny or New Jersey,there's no gas to pump,unless you want to wait for hours

 

Check your owner's manual - there's a sentence or two about not completely filling the tank and getting bogus gauge readings.

 

He speaks the truth. Pretty regulated is an understatement.

 

If you wanted to really check -

You could always stop in with a 5 gallon can with marked increments, and use the exact same pump and grade of fuel. If you pump 5 gallons on the screen and get less than that in the can, go call the commissioner's office and tell them the pump is faulty. Another way is to weigh the can once you have pumped it and see if it matches the weight of gas - 6# per gallon.

I figure sometimes you get shorted and sometimes you get away with some extra...

Does your car's gauge go through the bottom half of the tank quicker than the top half? Almost every car I own does that.

 

The only shorting I figure is typical is when you pump gas at a one-hose-for-all-grades pump (quite common), and get premium. you know the hose and pump are full of the lowest grade fuel, so you get a bit of that first. Hence its important to only fill up most of the tank to minimize the effect of the low grade fuel on the car.

 

I was told that the pump syphons the gas in the hose back to the station tank and there is no mixture.

 

There is in fact a mix that he describes but it is minimal. You are talking about the amount from the nozzle to the inside of the pump and I am guessing a fifth of a gallon at most. Blenders in the pump pedestal actually blend premium and regular to make midgrade. This is hyper regulated as well. In Missouri, the "Division of Weights and Measures" is setup to do just this. They surprise test for accurate metering as well as octane multiple times per year. As they should.