US firm Paice launched a similar patent-infringement dispute with Toyota in 2010, claiming the Japanese manufacturer had infringed its 1994 patent for a hybrid system. After years of battling, the two companies eventually settled outside of court, allowing Toyota to continue producing its hybrid vehicles.
Paice claims Hyundai's Sonata Hybrid and Kia's Optima Hybrid (neither of which is sold in Australia) use the same sort of hybrid powertrain technology that Paice patented in 1994.
A lawsuit was filed last Thursday at the Baltimore federal court accusing the companies of infringing three patents. It's understood both Hyundai and Kia were aware of the dispute with Toyota.
Ford has in the past agreed to license Paice technology to avoid further court action.
Paice is looking to stop Hyundai and Kia from producing its hybrids, and wants cash compensation. In a statement, the company said, "since as early as 2004, Paice has contacted Hyundai on numerous occasions and offered to discuss its patented hybrid technology".
Court action is expected to commence soon.