How the estimate is built
Duty is charged on the CIF value — the car plus freight plus insurance — and VAT is then charged on the duty-inclusive total. The fixed items sit outside the dutiable value, which is why they do not scale with the price of the car. The only thing that changes between the two destinations is the duty rate, and it changes enormously: 6% into a free zone against 60% for the same mid-size petrol car on the mainland.