The one useful thing that I learned from my crazy uncle was how to pump another gallon or two of gasoline by shaking the whole car to let the air out of the top of the tank. I later learned to not do that with passengers in the car--he somehow always got away with it.
Some gas station operators have noticed me *ding*-ing the "pump-finished" signal a few extra times, but seemed glad enough to sell me a few more dollar's worth of gasoline. I started to design a car-shaker for them to increase their sales, but decided that there is a far simpler method to get the bubbles out of a gas tank.
Quite simply, build the parking area around a gasoline pump to slope downhill away from the pump by a few degrees. This would allow the air that accumulates at the flat top of almost all gasoline tanks to bubble out. (Almost all drivers park with the filling port toward the pump, except me when I drive my mom's car.) The exit of the air would allow another gallon or so of gas in the tank for anyone who is filling it all the way up. Which would mean a few more dollars for the gas station owner.
There may be some good safety reasons for not filling a gas tank all the way up, but I am assuming that gas station owners will prefer to sell more gas than to worry about customer safety down the road.
The cost of building a station with a slight slope is probably no higher than the cost of a level station. The cost of retro-fitting a slope to an existing station will vary.
The ideal slope will be only a few degrees. The slope should not be enough that customers have difficulty getting car doors open or climbing out.
(My apologies to British readers for using American terms. Please substitute, where appropriate, the words "petrol", "pound", "horseless carriage" and "firkin". :)-- baconbrain, Dec 29 2006 How do you fill a car that has the tank opening on the rear of the car?-- Jscotty, Dec 29 2006 The same way as usual.
But yes, the tilt would possibly trap more air in a rear-fill tank. Not much more than usual, I think. There are so few rear-fill cars around here that I forgot about them entirely. I think that the gains to side-fill tanks would far outweigh losses to the few rear-fill tanks.
So this idea is for gas-station owners in areas where side-fill cars predominate.-- baconbrain, Dec 29 2006 The big benefit comes to those gas station owners as you drive away and your overfilled gas tank drains into the carbon filter and evaporates into the atmosphere. That is one gallon of gasoline they can sell you that you will never get to use.
Of course the EPA won't be very happy-- Galbinus_Caeli, Dec 29 2006 On some horseless carriages, there is an anti-overfill device - I think it's some kind of float valve. There is a way for one's chauffeur to defeat it manually, but the designed air space in the tank is to allow for thermal expansion, so overfilling is only recommended if you plan to continue driving for some time. So if the firkin thermal expansion of petrol is so important, may I suggest that it be chilled in the cellar before decanting it, thereby ensuring the maximum quaffage.-- Ling, Jan 01 2007 Hey! That wasn't us in Iraq. I mean, Yes, we did put those guys in power, and Yes, we set up their system of justice, and Yes, we are supporting them financially, logistically, and militarially, and Yes, they would be the first ones up against the wall if we blinked, and Yes we pay their salary. But we didn't do the actual hanging. (Even though we probably bought the rope.)-- Galbinus_Caeli, Jan 02 2007 random, halfbakery