A tangent ... It may not be unusual - actually it's mainstream now (q.v. above comments re earning miles by flying) - but it's taken to the extreme: Turbocarging mile-earning credit cards. There's a better term.

A couple of regulars at the DOs I sometimes attend claim to have done over 1,000,000 mi./yr. As I don't do it, some of their m.o. are .

...OK, quaintly naive?