well what about this would it be cheaper to fill up more often but fill with less gas like for instance every time u go fill up u only put a 1/4 or a 1/2 off the tank because theoretically ur car would be lighter when u drove around so it would waste less gas rather than driving with a full tank wich would make ur car heavier wich in turn would make it work that little bit more just to pull around those extra pounds of gasoline?

And if these is true does a lighter person save in gas compared to an obese person?