As others have said, 'gas' here in the UK (where this website is based) means the stuff that is fed through pipes to heat our homes and to cook out food. As you've posted in Motoring, I'll assume that you're in the USA and referring to what we Brits call 'petrol',
The first thing to note though is that you might not get too much sympathy from Brits if you moan about the cost of putting fuel into your car. We currently pay, on average, the equivalent of US$8.13 per (US) gallon, which is about 2½ times the current US average price.
However I suggest actually writing down all of the journeys you make (or anticipate making) by car and thinking carefully about whether they're really necessary. For example, if you make shopping trips on 3 days per week to one store, and on 2 different days to another store, would it be possible to do just one big shopping trip (on a single day) instead. Or perhaps you could just use your local corner store more often, and cut down on the visits to the big supermarkets.
Similarly, if many of your journeys are to and from work, have you considered car-sharing with a fellow employee, using public transport or, if it's within a few miles, simply walking?
Remember to do the really basic things with your car as well, such as weekly checks on the tyre pressures. Using your car with incorrect pressures can easily add 10% to your fuel costs. Try to drive at around the optimal speeds for fuel efficiency, which usually means between 30mph and 40mph, wherever possible. Use the accelerator slowly, allowing time for your car's speed to build gradually, rather than putting your foot hard down.
If you get the chance to change your car, consider manual transmission ('stick shift') rather than automatic. It will save you up to 20% of your fuel costs. Also consider a diesel vehicle or simply put fuel economy at the top of your list when making your choice of model.