“Economic” or “Economical”?

“Economic” and “economical” are two adjectives that are frequently used interchangeably. They are clearly related but they have, strictly speaking, quite distinct meanings.
     According to the Oxford English Dictionary, the definition of economic is related to economics or the economy.
     Economical, however, means “giving good value or return in relation to the resources used or money spent; sparing in the use of resources or money”.
     So, government policies to do with finance would be economic but fuel-efficient cars would be described as more economical.
Economic means, primarily, of or relating to the economy or economics.
Economical means prudent, efficient, or thrifty