Improving on a 'best-in-class' NVH performance

In the lead-up to launching the original cee'd, Kia Motors made an unprecedented commitment to improving its all-new C-segment model's refinement and durability. The company was determined that cee'd would constitute a 'qualitative revolution' for the brand.

Kia's cee'd engineering teams at the company's R&D Centre in Russelsheim were tasked with creating a new C-segment challenger that matched or beat competitor vehicles for minimising noise, vibration and harshness (NVH).

They achieved their original goal and now the same teams have made painstaking, small detailed changes throughout the new Kia cee'd to reduce cabin noise even further - by between 0.5 dB and 1.0 dB, depending on model.

The bodyshell for new Kia cee'd is carried over from the original and makes an excellent foundation on which to build a low NVH vehicle. Torsional (twisting) stiffness is 42 Hz and flexural (bending) rigidity is also high. The resulting strong structure delivers numerous benefits in terms of controlling NVH, enhancing occupant crash protection, and providing a firm base for the fully independent suspension.

A significant reduction in the transmission of road noise is achieved by the use of a front sub-frame to support the engine, transmission, suspension and steering, and a rear sub-frame for mounting the rear suspension - delivering many positive effects on NVH and isolating the cabin from vibration sources.

Aerodynamically, new Kia cee'd is a smooth, slippery and efficient car with a Cd of just 0.33 - minimizing airflow disruption over the car, and consequently achieving low levels of wind noise. The perception of low wind noise from within the cabin is aided by the fitting of multi-layer rubber seals around the doors and tailgate and one-piece weather strips around all windows.

Revised suspension settings and bushes, plus a new Michelin tyre structure, means that new Kia cee'd is better able to absorb vibrations and shocks from imperfections in the road surface.

Kia engineers focused their NVH-reduction push on minimising vibrations, both at source and by extra dampening, over a wide range of frequencies. Each panel of the cee'd bodyshell was scrutinised to identify areas which could be modified for new Kia cee'd to reduce noise generation at source. Hollow sections of the shell, especially in the A, B and C-pillars, were injected with sound-proofing foam, while isolation pads, made in new advanced materials, were placed in key locations.

Models fitted with the all-new 1.6-litre 'U2' diesel engine and new six-speed manual gearbox, also benefit from the improved refinement offered by this powertrain.

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