PARIS MOTOR SHOW: Kia Optima T-Hybrid

The next-generation Kia Optima that will be unveiled in the first half of 2015 could be packing an ultra-efficient twin-charged hybrid engine.

It would become the second Optima hybrid car from the brand, after the petrol-electric Optima medium car sold in the US. That vehicle was deemed too expensive for Australia.

The current range is priced between around $31K and $40K.

Kia's powertrain experts have been busy developing a new hybrid diesel engine that makes use of a turbocharger and supercharger for the combustion engine, along with an electric engine to provide low emission transport.

As it stands, the Kia Optima T-Hybrid's powertrain appears production-ready, making use of the brand's 1.7-litre four-cylinder turbo-diesel engine that gains an electrically-driven supercharger to "boost torque and engine response at low engine speeds".

The twin-charged diesel-engine is hooked up to a small electric motor that is powered by a 48-volt lead-carbon battery. The Optima T-Hybrid can be run purely on electricity when driven slowly or while cruising, says Kia.

Although most car-makers choose lithium-ion batteries to power their modern hybrid cars, because they generally have increased storage capacity, Kia says the adoption of a lead-carbon power source was chosen because "they require no active cooling and are easier to recycle at the end of the unit’s lifecycle".

It would also help keep costs down.

Other changes to the new mild hybrid powertrain include the fitment of a stop-start system and a new belt-driven starter generator. The latter replaces the conventional alternator, which Kia says results in almost silent and vibration-free engine restarts.

No fuel efficiency or power output figures have been revealed yet but the company is expected to divulge more info later in the week, when the 2014 Paris motor show begins in earnest from Thursday October 2.

Although the chances of the new diesel hybrid powertrain being offered Down Under in the Optima are slim, Kia Australia's chief of Media and Corporate Communications, Kevin Hepworth, said there is a glimmer of hope.

"You never say never," he said. "We will look at every single opportunity that comes our way. And on that basis, a hybrid diesel Optima would be considered for Australia."

The earliest deployment of the production-ready hybrid engine could happen next year. Kia claims the engine promises to reduce CO2 emissions by 20 per cent, while boosting power by the same amount over the current 1.7-litre oiler's 100kW.

The next-generation Kia Optima is tipped to debut at a major motor show in the first half of 2014, potentially a US event (Detroit is in January, New York in April) and Hepworth said in a "best-case scenario" we could see the all-new, still-secret Optima arrive on local shores late in the third quarter of 2015.

Whether next-gen Australian-spec Optimas are offered with a twin-charged hybrid diesel engine is another question altogether.

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