Unconventional wisdom – extending range with engined fuel pod

Aerodynamics engineers in the car design business have know for years that vaccuums can be used to reduce or eliminate drag on a body, in some cases even add negative resistance. Why don’t airplane engineers use these principles to extend range when using external fuel tanks?

In theory you could use low thrust cheap expendable engines, possibly no more than the Williams used on a cruise missile, to make a typical 2000L tank zero drag.