Thank you all for the responses, I really appreciate the information/advice. I feel like I'm still unsure of what to do. I understand a lot of it is how I drive, and I'm not 'perfect' - but I would say I am above average when it comes to being efficient while driving. When I'm on the road for long periods of time, I am normally setting my cruise control to the speeds I posted above and not changing lanes to pass people just for fun. Right now I'm driving a 2007 Mitsubishi Outlander and getting about 360 miles per fill up. Which means I'm filling up almost every other day. What's the min/max per fill up to expect on the FFH? What are some good Diesels out there? One issue with the Diesels though is that every gas station doesnt carry diesel gas, right?