Rick,

That's what I assumed since lanes were marked with speeds in some 
locations.  Except:

1) Some trucks have 2 such stickers with different values.
   Sometimes different colors, sometimes not.

2) The only cars that I noticed them on had much higher top speeds
   than indicated.  Such as a VW Polo with an 80.  Perhaps a joke?

The learner standard that I've seen in many countries (including Spain and 
Portugal) is a big L.  There were many time when I wished that I had one on 
my car!

Any further thoughts?

Thanks,
Mike