Mine came to Canada in its own 20' container. If you're the sole user of the container then it is sealed at the departure end and should not be opened again until the inspection point at port of arrival, so of the two conflicting recommendations up-thread I'm firmly in the "fill it with extra items to save weight in aircraft baggage" camp. Mind you, I've only done it once and had nothing go astray, and TerryG obviously had a very different experience!
Like Arwyn, I was dinged (by the Canada Food Inspection Agency at the Port of Montreal) for what felt like the most expensive car-wash in history, after they found a bit of mud in a tyre tread. $600 by the time it was done: moving the container "in-bond" through a bonded carrier to a secure facility, washing the car, collection and "safe disposal" of the dirty water, and moving the container (with still-damp car, grrr!) back to the intermodal depot with a new customs seal on the door.
After clearing customs it was then passed to an intermodal depot to continue its journey to Toronto by rail; it ended up in a transfer yard on the outskirts of town from where I drove it out of the container and home to prepare it for safety certification and licensing (I subsequently discovered that I'd been ill advised on this last point and ought really to have had it trailered, but nobody including my insurer batted an eyelid at the prospect of the car being driven around on UK plates for a couple of weeks...).
So, to summarize from my experience:
- Do take a sole-use container rather than groupage, so you can ensure the tie-downs and "dunnage" are adequately secured and can witness the security seal being applied
- Do try and get some sort of certification that the car has been adequately cleaned - try to find out what will satisfy the receiving country's inspection agency
- Do ensure you know what the rules are for driving a "visiting" car on foreign plates, and ensure you have adequate insurance
- Don't take the shipper's standard maritime (shared risk total loss) insurance - use a third-party broker to get the coverage you need
