The API accepts whatever you give it, which it then tries to make sense of.
This spreadsheet may not be entirely up-to-date, but it shows a
minimum state (the actual result could be better than indicated). It
shows that geocoding in India is "same as tiles", which I doubt
includes postcode data.
http://gmaps-samples.googlecode.com/svn/trunk/mapcoverage_filtered.html
If you do include postcode data for countries which are shown as "same
as tiles", the API is likely to get confused.