I've been trying different driving styles for a while now, in an effort to reduce my fuel economy and tank range. I've found that I get the best results when racing around, as opposed to driving particularly slow or carefully. What's going on? Also; how can I calculate the ideal range to shift (etc.) to achieve my goal? Thanks in advance.

I've been trying different driving styles for a while now, in an effort to reduce my fuel economy and tank range. I've found that I get the best results when racing around, as opposed to driving particularly slow or carefully. What's going on? 

Also; how can I calculate the ideal range to shift (etc.) to achieve my goal? 

Thanks in advance.