The following link will provide you with all the
details on German WWII color schemes:
http://www3.sympatico.ca/wmburns/Bmisc.html
In short, from 1943 all new vehicles were
factory coated with Dunkelgelb which is dark yellow.
As Pierre has already mentioned, crews in the field
were supposed to apply camo using Olivgrun
and Schokoladenbraun (dark greeen and brown) which
resulted in numerous variations of actual camo patterns.
Repaired vehicles were NOT repainted, though, so that
color schemes with camo colors applied over Schwarzgrau
are still possible after 1943.
The problem with "Patton", IMHO, is that 90% of the AFVs
used there are fairly modern ones. The question of correct
or incorrect color shemes becomes a minor thing in such
situation.