If you're using that much gas, you could drive something smaller. I fill up once every two weeks, for about $30.
Why? I like my car.....
Let's see... I live in a rural area and have 3 kids (with a 4th on the way). My mini-van gets 20ish miles to the gallon and my job is 12 miles each way from home. Add in baseball practice & games for the 3 boys 4 nights/week, dropping my step son off at his birth mother's every Saturday, going to the grocery store, pharmacy, etc. and I'm filling up once a week for about $60.
What vehicle do you recommend that is smaller but would still hold my husband and four children in addition to getting me to/from work every day? My husband already drives an 1988 Ford Escort because his job (like so many other people in our area who must commute out of the county for work) is 30 miles each way - but his vehicle will only hold 4 people total - not exactly a "family" car.
My husband and I work opposing days and hours to keep our kids out of daycare (which also means they go wherever we go, all the time). It's a boatload of fun grocery shopping for a family of 5 with 3 kids in tow. I've done it at midnight just so I didn't have to bring the babies with me.
But to do it in an economy-sized car? No thanks. I'll pay the extra right now, because until I'm out of the carseat/booster seat phase, smaller won't work.
Not everyone can drive smaller cars. Depends on what you do for a living.