OK so for my house to work is 6.7 miles. Half that is interstate. And I weigh 170lbs. My tires are inflated correctly and I've been getting gas at shell religiously. My dash says I should be getting 48.5mpg. I filled up at 69433 a week ago. Today I'm at 69509 and I just hit my red E line. I know no one can really tell me what is wrong but I don't see any gas on the ground so I'm wondering what steps I can take to fix this or what to look for.