On multiple occasions, the HEV system warning light and check engine light activated while I was driving at highway speeds. Immediately after the warning lights appeared, the vehicle suddenly decelerated, putting me and other drivers at risk. This issue has occurred several times and is clearly a serious safety hazard. Each time this occurred, I brought the vehicle to an authorized Kia dealership ([Dealership Name]) for inspection. However, despite the vehicle being under the Kia hybrid system and/or powertrain warranty (10 years/100,000 miles), I was recently informed that the necessary repairs would not be covered under warranty.