this has been going on all the time in colorado and a few other places.
  it is only for vehicles where the gas cap seal is actually part of the
emissions system.  this would be many cars since about 1990.  many
injected cars actually pressurize the entire fuel system and this keeps
fuel vapors from being pumped into the atomosphere, and on some cars it
definately effects your performance as well.   on some cars a
diagnostic check actually has a step to check and make sure the gas cap
is sealing correctly.
jimt
On Wednesday, Nov 13, 2002, at 18:58 America/Denver, Joseph Fortino
wrote:

> smog check now checks gas caps for pressure? total weirdness if you
> ask me
> it can fail the test if your cap has a micro crack?? anyway heads up
> calie4nia people
>
> another rule in the world of cars!
>
> Joe
>
>