What are some reasons why driving a fuel-efficient car is beneficial for themselves, their community, or the nation?

A fuel efficient car can be beneficial to all of these. 
For example:

• It benefits the individual because
  it ends up costing them less money in gasoline.  This can amount to a great deal of
  money if gas prices stay as high as they are and/or the person drives a great
  deal.


• It benefits the local community because it can
  reduce the amount of pollution in that community.  If more people drive fuel-efficient
  cars in a given community, less fuel will be consumed and less exhaust
  expelled.


• It benefits the nation by reducing the nation's
  dependency on oil.  This is very important given that much of the oil we use comes from
  politically unstable places like the Middle East, Nigeria, and Venezuela.  Less oil
  consumption means more energy security for the country as we rely less on these
  countries to supply us.