There are several ways to travel to Sweden. You can drive and come from Kiel by ferry to Göteborg. This way to travel is the most expensived one but also the relaxed one to Sweden.
The Travel by car will will take you from Kiel 13,5 Hours, If you like Denmark, you can also go to Frederikshavn and take the ferry to Göteborg, the traveling time from frederikshavn is 2,0 to 3,5 hours.
Whoever likes to travel by car and likes to see the nature of Sweden, should use the route from Puttgarden in 45 minutes to Rogdby and from there over the Öresundbrücke, or further through the Bird flight route.
In Sweden you follow E6 towards Oslo until Uddevalla, from there you take the country road 172 towards Bengtsfors. In Bengtsfors you stay on the country road 172 towards Årjäng, after 25 kilometers you are in Gustavsfors.