In my limited experience with cars, but general knowledge, it's Japan, no contest. American reliability has really gone to hell in the past 20 years. I can't say Germany because i've heard too many horror stories about VWs breaking, and costing thousands of dollars for very minor repairs. I would say Sweden, but both of their major companies (Volvo and Saab) are owned by American companies, which led to their demise. My thought on Korea is that they give you a 10 year warranty because they are fairly shotty cars.