The carmaker is to expand its manufacturing plant in Georgia – which also produces the Sorento SUV – from September 2011 to raise annual capacity to 360,000 vehicles starting in 2012.

The $100 million project will see a series of expansion projects in each of the plant's four main shops – stamping, welding, paint and general assembly.

Byung Mo Ahn, group president and CEO of Kia Motors America and KMMG, said: 'Kia is experiencing unprecedented growth in the US, led by the best-selling Sorento, and with demand for the critically acclaimed Optima currently outpacing supply we are proud to add the popular sedan as the second Kia vehicle on the production line.'