A parking sign at my local library

"For fuel efficient cars only." How is one to know if their vehicle complies with this? I drive a Honda CR-V and get over 20 mpg.

Small cars

About the only enforceable parking sign is the handicap spaces.

If there reserved for expecting moms, seniors or fuel efficient cars then the parking space is fair game, it's a courtesy not a law. Although it won't be to long before cash strapped states adopt this stupidity as an enforceable law for some quick cash.

Check your state and local laws. In most places that is a courtesy sign and can't be enforced by the police. If it is based on a law or ordinance, it would probably define what a fuel efficient car is.