KIA saloon the Optima will feature both hybrid-electric and plug-in hybrid-electric power within the next 12 months.

They will be part of the Korean brand's range of new engines - part of its plan to further lower the emissions of its vehicle line-up.

The Optima Plug-in Hybrid (PHEV) is set to go on sale in the second half of next year, offering increased battery capacity and pure electric range.

Meanwhile, the new Optima Hybrid (HEV) will offer buyers improvements over the existing variant, heralding a larger battery pack, more powerful electric motor and revised transmission.

Kia says the changes should contribute to a 10% improvement in fuel economy over earlier versions when the HEV hits the streets in the first half of 2016.

It will feature a battery pack with around six times the energy output of that found in the current-generation Optima Hybrid.

And paired with a 50kW electric motor - itself 42% more powerful than in the previous version - the combination allows the Optima PHEV to operate in pure-electric mode at higher speeds.

Engineering teams working on the car expect it have the ability to travel up to 27 miles on electric power alone.

In tandem with the 2.0-litre petrol engine and six-speed automatic gearbox it gives the Optima a total power output of 205PS.

Engineers are targeting 48mpg combined in charge-sustaining mode and once plugged in, the PHEV will recharge in less than three hours at a 240V Level 2 charging station or nine hours from a standard 120V power outlet.