Karlsborg is a village located in the Municipality by the same name, in Västra Götaland County, Sweden. The area grew due to the building of Karlsborg Fortress, should there have been a war it was to be the capital of Sweden. Hiring a car in Karlsborg gives you the freedom to explore the area. Given Karlsborg's relatively isolated location, you'll need a hire car to get you into bigger cities. Closeby is Skövde, if you're visiting in summer there is a food festival held across the last weekend of August, which celebrates the restaurants in the city and gives you chance to sample them all.
Rent a car in Karlsborg to explore the fortress on which the area is focussed. Karlsborg as a village developed as a secondary to the fortress to home the staff working at the defence. The vast expanse of the fortress gives a lot to see and is a main attraction, with exhibitions and tours available. Bigger cities are quite far out, but worth a visit if you want some bigger attractions. Hire a car in Karlsborg and create an itinerary from your base. There's plenty around Sweden to explore, depending how long you're in the country.