Bolivia's population has increased sharply recently, while Sweden's has been growing much slower if at all. So historically Sweden doesn't look so small, and they share (somewhat) a labor and goods market with Germany, which has a huge domestic car industry and correspondingly offers the goods and services that car manufacturers need, and Denmark nearby, with shipping on the Baltic offering multiple excellent ports. Historically, in 1950 you have Sweden at 7M and Bolivia at 2.7M. Sweden is an outlier among small countries with its car industry thanks to all of these factors.

Additionally, while not all of Bolivia is mountainous, the sweltering tropical climate of the lowlands is not exactly germane to physical toiling in a factory building all day. And my point about labor resources includes diversion from other more worthy applications of the abilities of Bolivia's engineers: its domestic infrastructure (power/transport/water) is lacking and you can't import that. Sweden has had a long time to build a power grid and rail system and enjoys less challenging geography.

Yeah, but Sweden industralized a century and a half ago.