Those japanese import cars are not grey market... they are imported, but were intended for the us market.. and therefore must meed safety / emissions, etc codes for import. The key is that they were manufactured, and intended to be sold in our market. The gre market yanmars for instance, were manufactured and intended for the japanese market.. not the us market.. when they get imported to a market other than the one(s) intended, they become greys.
I would wager that a jap car imported here, then sold and taken back overseas, would then be a grey market car.. in its own country of origin.. as it was not intended for that market.. etc.... what a thought!
Soundguy