I'm in Dfw, and have to drive about ~20k/year. I'm pretty happy to get the average 30+mpg I'm getting with my Focus. That's about 55 gallons/month, so a bit over $220/month on gas already. I can imagine I'd be feeling a lot of pain if I was getting 15mpg mixed like a few people I know. A trip to a destination in the area 30 miles away and back would be 4 gallons, or $16 in fuel alone, or $8 more for that single trip. That tends to add up quickly, and there are more important things I can spend my $$ on.
I want something more fun to drive eventually, but it looks like it will have to end up being a 2nd/spare car.