http://money.msn.com/saving-money/article.aspx?post=9178878e-62c1-46d4-80eb-849f4fb2a7fe>1=33026
I'm calling bull**** on number 7, for the simple fact that gas cannot defy gravity and travel upward without help.
I agree...
Many fuel cells are pressurized, so in essence the liquid could defy gravity in the absolute perfect situation, but the odds are slim to none. Most fuel systems at this point will only let fuel over flow while the cap is off. Also, fuel going back into the stations tank is almost imposable. First off, only a small percentage of the areas of the country have stage three vapor recovery, which is a vacuuming system to recover vapor as you fill the tank. Generally, even an old school fuel fill nozzle will shut off the flow before you could spill a lot, or the vapor recovery system could suck up any liquid if it was actually drawing enough vacuum.
Changing your oxygen sensor is a waste of money for the most part. While they do fail from time to time, they don't really have a service life on most brands, and it's just a money maker for the shop. I think GM came out with changing it at a pre-determined mileage interval. They can last for the life of the vehicle doing their job within their operating range. When they go bad, you'll normally get a trouble light shortly after, and a trouble code for a rich running condition. Modern engine management systems have a nice range of compensation, and with other inputs to the ECU, even an oxygen sensor that is at the outer edge of it's operating range, is not going to throw off the running of the engine enough to really throw off your fuel mileage.
Tire pressure will effect your mileage if your one of those people who never checks the tires, and depends on it being taken care of at oil change intervals. In 3K, you can easily be 15 PSI low. I actually proved this to my daughter a few weeks ago. She had done a trip on the highway. About two weeks later, I checked her tires, all were low, and I adjusted accordingly. She did the same rout the next day, and did get slightly better mileage. A bout 13 miles on a tank full, and that's not a lot, but it is a gain. The new tires are a gimmick in reality, but proper inflation is key to getting the max mileage.
The real key to getting the best mileage you can is really a combination of things you can do. Tire pressure, regular oil service, and fuel injector cleaning from time to time will keep your mileage at the max. With all the junk they put in gas these days is causing so many problems. A fuel injector is meant to deliver a fine mist (atomized fuel /air mixture), but when they get dirty, you'll often get droplets of raw fuel... not atomized, and it will give you a rich condition, and poor fuel economy. You can get the same condition with carbureted vehicles too, so keeping the fuel system clean is one of the most important thing you can do.