So I put $20.00 of gas into my Civic yesterday and I've only driven about 42 miles since. How much gas mileage do I get out of my Civic b/c my gauge is showing that it's on a quarter tank already!!! I know that is some bull**** b/c $20.00 worth in my Civic usually puts me a little over half considering the gas prices these days. Could there be something wrong with my gauge or do I have a leak?