MPG may not be the most intuitive way to measure fuel efficiency, but it is certainly still linear. 50 MPG actually is 50% less efficient than 75 MPG.
Lowest cost option is to just buy the paperback (used or new), read it, and sell it back on amazon a month later.
But to make money (directly) you have to offer a dubious protection device after scaring them.
Not if you are a news organization that attracts viewers with scary headlines.