One can do a full switch over to hydrogen and they won't have to pump another gallon of gasoline.

Or one can keep their ?training wheels? on and convert partially to a gasoline/hydrogen hybrid system. That is even simpler to do. And it will reduce your gasoline consumption, usually by a bit more or less than 1/3rd.

But aside from that there are two other suggestions that I felt would be helpful to?.

There are different views about whether our MPG improves when you fill your gasoline tank when it gets half empty compared to when the tank gets nearly empty and has to be refilled. The advantage to a fuller tank is that it helps keep air out of the tank space. Having your tank full lessens condensation in the air from getting into the gasoline.

The other suggestion for today is that the fuel filter may need to be changed if you notice a difference. Keeping the tank more full is also more efficient for the gas fuel pump. I have done it both ways for a long time. I usually refill when my tank is half empty.
Also regarding your gasoline filter, I suggest keeping a new one in your vehicle. If the fuel filter is more that five years old, get a new one. A slightly plugged filter will weaken the mixture and can lower the MPG. A full tank has a higher head which helps facilitate the job of the fuel pump. Fuel filters need to be changed about every 15 to 25,000 miles but many drivers go longer than that before the filter gets replaced.

Those are two easy tips. But the real solution is convert your gasoline system to hydrogen! Your automobile will love it! So will your bank account!