Should I buy a more fuel efficient car? Is it worth it?

My new job is a 40 minute drive (highway). So 80 minutes a day. I currently have a car that gets roughly 27 mpg highway. I really like my car. It's not good in winter though (I live in IL). My payments are $351/month. I'm worried that the added gas costs will bring me down. But buying hybrid/highly fuel efficient car would be fairly expensive monthly payment-wise. So would it be more wise to keep my car and pay extra in fuel costs or buy a new efficient car and pay more in monthly payments? I don't have any money saved.