Kia Optima Hybrid revealed in LA

Kia has revealed a hybrid variant of its new Optima sedan at this year's Los Angeles Auto Show. The unveiling presented the company with an opportunity to showcase its newly developed full-parallel hybrid system.

Kia claims the system delivers a class-leading fuel economy figure of 5.8L/100km on the combined cycle, a 40.7 per cent improvement over the conventionally-powered variant. At the same time, Optima Hybrid achieves petrol sedan-like performance with the 0-100km/h sprint managed in just 9.2 seconds and a top speed of 195km/h.

Kia says the impressive figures are the result of its "ingenious, simple and cost-effective" parallel hybrid system. A 2.4-litre four-cylinder (154kW/265Nm) petrol engine is mated to a small (30kW/205Nm) Interior Permanent Magnet synchronous electric motor driving the front wheels via a six-speed automatic transmission.

In lieu of a traditional torque converter, Kia has employed an electric motor, high-efficiency oil pump and laminated-type wet clutch that allows the petrol engine to be de-coupled from the powertrain so as to allow full electric operation.

Described by Kia engineers as a Transmission-Mounted-Electric-Drive (TMED), the electric motor sits within the car's extended transmission casing (between the petrol engine and the automatic gearbox) and is the world's first oil-cooled system. The system's configuration also does away with the high-capacity electric motor and generator found in many hybrid systems, saving both weight and cost.

The electric motor switches into hybrid operation and serves as both a secondary engine (during full acceleration and hill-climbing) and a generator to recharge the battery pack as necessary.  Whenever the car comes to a stop for more than a few seconds, the engine automatically shuts off to completely eliminate emissions. Optima Hybrid can effectively operate in all-electric mode from rest to 100km/h, producing zero emissions.

"The new Optima Hybrid features a unique architecture and is packed with innovative technologies that demonstrate Kia's on-going commitment to investing in R&D, and to developing environmentally friendly vehicles for the future," explained Vice-Chairman of Kia Motors Corporation, Mr Hyoung-Keun Lee.

"Although these new technologies presented our engineers with a series of complex challenges to overcome, the resulting Optima Hybrid delivers a fully automatic, seamless and enjoyable drive, together with real-world benefits for our customers."

Powering Kia's electric motor is a boot-mounted lithium polymer battery pack developed in partnership with LG Chem.  The pack provides an optimum balance between power delivery, energy density and thermal stability, and compared with nickel-metal hydride batteries is 10 per cent more efficient, weighs as much as 30 per cent less and occupies up to 40 per cent less volume. Kia says the 43.6kg battery pack will not require replacement during the vehicle's lifespan which is at least 10 years and 250,000 kilometres.

The complete hybrid system is controlled by the Optima's Hybrid Control Unit (HCU) which integrates the function of engine, transmission, battery pack and voltage converter. The HCU also gives Optima Hybrid a fail-safe back-up capability and "limp-home" mode. All the HCU's functions are displayed on the car's instrument panel.

Further improving the car's petrol engine efficiency, Kia has modified its 2.4-litre Theta II engine to operate on an Atkinson cycle, raising the compression ratio by 20 per cent and reducing fuel consumption by up to 10 per cent. Although altering the engine in such a way does reduce its torque, this is more than compensated for by input from the electric motor.

The all-new Kia Optima Hybrid will go on sale in the US early next year but is not yet slated for Australian release, Kia's local representatives saying it's under consideration.

"It is certainly something we are considering closely as we move forward with Kia's increasing exposure to alternate fuel technology," said Kia Motors Australia Chief Operating Officer, Tony Barlow.

"This is the sort of well-considered and developed technology that is now a cornerstone of Kia's expanding model range."

The petrol-powered Kia Optima will go on sale in Australia from January.

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