I've already shipped the car from USA (Bayonne, NJ).
It wasn't difficult to send car to Poland but it was difficult to find Customs Agency.
I found it.
If u have any problems please contact with Peter from TAKSIM-POL Agency.
They caen organise customs clearance in Gdynia or make transit clearance and u can make customs clearance in your city :)
He speaks english and polish. Phone to This company (058) 627 40 71
This company made me customs clearance.
So don't worry, everything will be fine :)