/AGREE!!
Less gas in your tank allows your fuel pump to burn up faster. I never let my car go below 1/4 tank of gas...my car still has original fuel pump... with 187,000 miles.   See 4 other replies

I hear you.
Apparently, Gemini is a female.The model T Ford Didn't have a carburetor.
So that isn't a fair comparison either.Turning the nozzle upside down might be good if the nozzle doesn't have the back pressure check / ball valve.In my experience,
The best ways are, like you said, don't carry bags of concrete in the trunk.
Most of all, Don't slam down on the gas pedal.
It takes more gas to accelerate to 70 in ten seconds than it does to idol for 20 minutes.
Plus the wear and tear on the engine, wheels and transmission.
Bring your car up to speed gradually.
You may pissoff the guy behind you but he'll find a way round.My car is an 07 Toyota and is rated for 34 in the city.
I get 41 and I have the A.C. going and the radio blasting.Granted it's a newer car and still within specs, good compression, good rubber.
By not driving like a maniac, I hope to keep it new.
Having a good cooling system with lubed water is important as a cooler engine is more efficient as well.
Depending how you drive, tire pressure can be an element as well.
You can go a few pounds over recommended for mileage, or you can go a few under for grip.   See 4 other replies

Or just obtain a successful career so you won't have to give a damn about looking cheap by rolling down your windows in your used 96 Buick or doing your own oil changes---but instead riding in your 2009 BMW with a/c in full blast while letting the dealership deal with car maintenance. Fuzzledice you poor cheap fool--you should've gone to college.   See 4 other replies