Fresh gas always seems to drive better, so what do you guys think of the idea only leaving 1/4 of the tank full and pump fresh gas for what you need to use for the day every morning? Anyone has done that before?
Depends on what you mean by "drive better." Chances are the gas has been sitting somewhere in a containment for months at a time before refining and shipping to your location and maybe a couple more days until you actually pump it into you car. Seriously? You can tell the difference?
If you're looking at getting the most out of your engine then just do regular maintanence (lots of oil changes, spark plugs and fuel pump/injectors occasionally, etc etc) and dump a bottle of fuel system cleaner in the car everytime you do an oil change. I personally use Chevron's Techron fuel system cleaner and it works magic.
IF you're not talking about our beloved NSX and you just want the best fuel economy, then just put in the lower grade gas possible (grade as in octance), because lower octane gas actually burns more efficiently BUT at a cost of engine problems. For our NSX and higher end engines its a no no because you'll get some knocking for sure. On the line of being fuel efficient, you can also buy a drum of acetone and mix it in with your fuel, does amazing job at getting better fuel economy (sometimes up to 10% better when i tested myself). Some claim to do even better. BUT AGAIN, sacraficing the fact that you'll probably degrade you fuel lines/components a tad bit faster.