Kia has started testing the prototype production line equipment for next year's Hyundai i35x crossover, which will be built at its plant in Zilina in Slovakia.
The Tucson replacement will become the first non-Kia car to be built at the Slovakian factory when production starts next year.
However the engine facility at the plant already makes identical but rebadged units for both manufacturers.
Sources say that, for marketing reasons and much to Hyundai's frustration, the ix35 will not be offered with the seven-year warranty that is standard on all Kias built at the hi-tech plant.
The car will instead come with Hyundai's traditional five-year deal.