In order clear the vehicle through customs, you must have the purchase invoice, bill of sale, receipt or other documentation to provide evidence of the value of the vehicle. You must also bring the foreign registration document.
The rate of customs duty varies for motor vehicles. For passenger cars, it is 10 per cent. The amount of the customs duty is calculated based on the purchase price, insurance and costs arising in conjunction with the transport of the vehicle to its point of entry in Sweden. You must also pay 25 per cent VAT.
When purchasing a vehicle from another country, contact the Swedish Transport Agency. They can help answer questions about registration, vehicle tax, registration plates, moving vehicles and verification of vehicle origin. More information on applications and required documentation can be found at their Web site, transportstyrelsen.se.
More Information
Swedish Transport Agency
Forms
Single administrative document (SAD) 
SAD guidlines
Publications
Importing goods
