Regardless of your take on global warming or who should be president and what fiscal and social policies should be adopted, we can all agree that it would be nice to save some green at the pump. Let us first take a look at all the gimmicks that have become well known. Items like tornado intakes, fuel additives and other bolt on items promise insane fuel mileage increases. Let us just suffice this entire category of items with the statement, save your time and money. If you get nothing else from this discussion, realize that such gimmicks are just that and will only cost you money that you cold have been using for gas anyways, essentially costing you more at the pump.
Now, what can you do to save a few drops of gasoline that make sense. For starters, ensure your tires are properly inflated. There is no need to over inflate and possibly cause an unsafe condition, just follow the manufacturers recommendation on the side of the tire (just be sure to inflate appropriately for cold or hot tires which is also listed on the side of the tire). A proper tune up can also pay large dividends and if you do the work yourself you can save even more. Majority of the things that you need to do maintenance wise you can do yourself. For example, changing spark plugs and wires as well as the air filter are quite simple with common household hand tools. If that isn't really your game, no problem. The next time you have an oil change ask your mechanic to change your plugs and wires (if they need it) and service the air filter. While you are at it, consider spending the extra money and converting to a synthetic oil. Synthetic oils have been shown to provide more power and better efficiency (read better mileage here) and many of the oils require changes less frequently, well offsetting the extra cost of the oil. Most importantly, consider adjusting your driving habits. Coast into stop lights, accelerate more gradually and maintain a speed 3-5 MPH below the posted limit (this will also provide a ticket free guarantee and an added safety bonus, not to mention wear and tear on your drive-train).
If you'd really like to save, make short trips walking ventures with your family and/or pets. Its healthy, enjoyable, free and it essentially increases your mileage and lowers maintenance costs. Of course you can also car pool where possible and consolidate trips. The bottom line is, in most cases there is no need to get rid of your car for a more expensive hybrid, nor is there a reason to go to ridiculous limits such as hyper-milage techniques that sacrifice safety to save gas and money.