S&P raised credit ratings on the three companies from BB+ to A-.
It was the first time that the three companies have received an A-level mark from a major international credit rating agency.
In an emailed press release, S&P said: "Given their improved brand and product quality over the past few years, we believe their recently announced capacity additions are likely to help them maintain their global market positions."
On Jan. 6, Hyundai Motor Group, the world's fifth-largest automaker, announced plans to invest 80.7 trillion won (approximately US$72.7 billion) over the next four years to, among others, obtain technologies for for future cars such as eco-friendly and smart vehicles.