The roads connecting the main Swedish cities are well maintained and pretty straightforward to navigate. Hitting multiple regions in a few days requires a reliable set of wheels to keep up with the tasks. You can look into car rental options in Sweden here:
https://getrentacar.com/en-US/sweden . The website filters let you pick out specific engine types and mileage limits for cross-country drives. Owners upload actual photos of the vehicles so you know exactly what interior trim you get. The chat feature allows you to directly ask the host about toll transponders or local parking rules.