Hi Alfred,
Hope you're well. I imported by car from the US via Bremerhaven (so Germany, not Holland). I used a very good shipping company from the East Coast (a one lady operation; wonderful; I'd be pleased to email you her details). She made all the arrangements, and I'd strongly advise that anyone shipping a car uses a forwarder. However, because I was shipping to my 'work' and because we're exempt tax, I can't really tell you about duty costs.
My car was collected from the port by a German transporter firm that brought the car to where I was based. It was all very simple and all arranged for me. I can give you a breakdown of the costs of each element of the shipping (I think). Drop me an email if you're interested, although I realise it's a different route to that you're enquiring about. A quick call to the lady I used will, no doubt, enlighten you further about the costs. She was most helpful.
My car was shipped on a car transporter, not in a container. I have a slight suspicion that some genius moved it with a forklift; it has minor dents on the underside, which is annoying. However, that may have been because the car wouldn't start. If your car is perfect, you may want to ask about the additional costs associated with a container move. I think it's about double. I also recall insurance was hard to get. I did it without insurance. I wouldn't do that now having put so much work into the car.
James