Kia Niro Technical Specification

Faults and Technical chat for the Kia Niro
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Rob
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Until now, dedicated crossovers have largely been much of a muchness, shaped by aerodynamic considerations above style, practicality and desirability. But Kia does not do elevator music. When embarking on the Niro project it decided to go for a modern, attractive crossover body style with ample room for five people plus their luggage. One remarkable feat is that this has been achieved with a drag coefficient (Cd) of only 0.29, even on versions with roof rails.

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The design features the subtly sculpted surfaces and sharp lines that instantly mark Niro out as a modern Kia, and includes the latest evolution of the brand's 'tiger-nose' grille as well as the familiar broad C-pillar. A wide stance gives pointers to the car's stability and low centre of gravity, while a long bonnet, short overhangs, elevated headlights and a rising shoulder line are other Kia hallmarks. The body tapers towards the rear, where bold wheel arches, a squared-off bumper with a diffuser section and high-mounted C-shaped tail lights emphasise Niro's crossover stance. There is body cladding beneath the front and rear bumpers, along the sides and around the wheel arches. A subtle roof spoiler aids the car's aerodynamics.

At 4,355mm long, 1,805mm wide and 1,535mm tall (1,545 with roof rails), the compact Niro sits between the cee'd hatchback and the all-new Sportage SUV in size. Yet with a 2,700mm wheelbase and short front and rear overhangs it provides generous interior space.

The styling of the high-quality interior features a wide dashboard set out on horizontal lines, with an upper display sector that houses the instrument panel and infotainment screen at the same height, separated by a cabin-wide trim line from the lower control area, where the heating and ventilation and driver assistance switches are located.

All-new hybrid powertrain promotes outstanding efficiency

Niro's powertrain, like its design, marks it out as something different from the norm in dedicated hybrid vehicles. While it pairs a petrol engine with an electric motor like the majority of hybrids, drive to the front wheels is through a six-speed double-clutch automatic gearbox (6DCT) rather than the more commonly favoured continuously variable transmission (CVT). This gives more direct and immediate response with greater refinement, and incorporates a Manual Sports mode to allow keener drivers to select gears manually.

The petrol engine is a new 1.6-litre direct-injection (GDI) unit, specifically engineered for use in hybrid cars. It develops 104bhp and 147Nm of torque, and conforms to Kia's policy of adopting high-efficiency downsized power units for all new models. The engine marks the first combination of an Atkinson combustion cycle, cooled exhaust gas recirculation, direct petrol injection and a long-stroke specification for maximum efficiency. The Atkinson cycle holds the intake valve open longer than in a normal Otto cycle engine and also reduces the compression ratio to extract a greater proportion of energy from the combustion process. Efficiency is further aided by an exhaust heat recovery system which speeds the engine warm-up process.

The combustion engine is paired with a 32kW (43.5bhp) electric motor developing 170Nm of torque and powered by a 1.56kWh lithium-ion polymer battery. Together, the two power units produce 139bhp, with 265Nm of torque available in first gear for rapid acceleration from standstill.

Niro is a parallel hybrid, which means that most of the time the petrol and electric power units work together. However, it can operate in all-electric mode for short distances when setting off, under gentle acceleration and when descending slopes or braking. A brake energy recovery system recoups energy normally dissipated as heat and stores it in the batteries for use later. The switch between all-electric, hybrid or petrol engine-only modes is seamless and varies according to the load being placed on the powertrain at any given time. This advanced powertrain ensures Niro is capable of up to 74.3mpg, with CO2 emissions from only 88g/km.

The in-house 6DCT gearbox incorporates a new Transmission-Mounted Electric Device (TMED) which allows the full output of both power units to be transferred in parallel to the drive wheels, with minimal energy losses. This differs from the power-split system typical of CVT transmissions, which convert a portion of engine output for delivery through the electric motor, resulting in a loss of energy. TMED allows the hybrid system to access battery power directly at higher speeds for swifter response.

An all-new platform exclusively for electrified vehicles

There will be no combustion engine-only version of Niro. Its all-new platform has been engineered exclusively for electrified vehicles, and a plug-in hybrid version (PHEV) will be introduced for the 2017 model year.

The platform has been designed to accommodate present and future electrical components within a compact vehicle footprint without intrusion into the spacious interior and luggage area. A slightly raised crossover-style seating position makes getting in and out easier and provides a superior view out.

The structure is particularly strong and includes 53 per cent advanced high-strength steel, which ensures that rigidity and safety do not compromise weight. This is aided by extensive use of aluminium for the bonnet, tailgate panel, front bumper back beam and several chassis elements, including the front knuckles, front lower arms and brake calipers. Even the parking brake pedal, which is made of fibre-reinforced plastic, contributes to the weight savings. To ensure body integrity and rigidity in critical areas, hot-stamped steel is used to reinforce the A- and B-pillars, roof rails and wheel arches.

Thanks to the long, 2,700mm wheelbase there is generous space for five people plus 427 litres of luggage space (373 litres with luggage undertray), even with all five seats occupied, thanks to the location of the battery pack beneath the rear seat. This expands to 1,425 litres (1,371 with undertray) with the 60:40 split rear seats folded. The 45-litre fuel tank is located alongside the battery pack beneath the rear bench.

No compromise in comfort and refinement

By re-engineering certain existing components, Kia has been able to ensure that Niro has a unique chassis specifically designed for a hybrid while being the equal of the brand's other compact models for ride comfort, handling and refinement

Niro's road behaviour begins with fully independent suspension all round, based on MacPherson struts at the front and a multi-link arrangement with dual lower arms at the rear. It has been tuned to deliver maximum on-centre steering feel, high-speed stability and immediate response to steering inputs.

Capitalising on the experience gained through the development of two generations of Optima hybrid (neither sold in the UK) plus the Soul EV, Kia has been able to give Niro consistent and linear deceleration characteristics and feel unusual in an electrified car. Electronic Stability Control and Vehicle Stability Management, which collectively control skids when cornering or accelerating on surfaces with uneven levels of grip from left to right, are standard.

Niro's exceptional refinement proved particularly challenging to perfect because of the hybrid powertrain. Contributing towards this are asymmetric engine mounts to minimise powertrain movements at the attachment points in the sub frame, high-density under-bonnet insulation, an acoustic shield with a special support structure to improve the sound of the combustion engine when accelerating in the most commonly used speed ranges, and the adoption of a 6DCT gearbox in place of a CVT.

Road noise is minimised by high-insulation rigid bushes in the front sub frame, high-strength steels in the rear wheel arches and additional insulation in the A- and B-pillars. The low drag co-efficient (Cd) of 0.29 contributes towards the suppression of wind noise, aided by laminated windscreen glass, a cowl over the front windscreen wipers, specially profiled door mirror casings and – as an example of the attention to detail of Kia's engineers – covers over the holes in the roof rack rails, which sit flush on the bodywork.

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