The regular Civic may not be the best dollar-for-mile value either considering there are a few base models available for about $10K such as the Chev Aveo, Kia Reo and Toy Yaris.

If one can get these in the base model I'm sure the savings could be astronomical but as stevenvillatoro mentioned there are many things to consider.

Efficient drivers do it better.
1003 miles a tank personal record. 74MPG calculated. HCH1 CVT