This study uses a modified cost function with weighted error signal channels to demonstrate that the vehicle active noise control system can focus control efforts on one specific seat. In a conventional active noise control system for road noise suppression inside a passenger car, the control algorithm targets the attenuation of all seats, hence affecting the maximum performance that can be obtained when applied to a single seat. To address this limitation, we employed weighting factors in the error signal to control the selected seat positions only. A practical active noise control system was implemented in a large sedan to investigate the effect of the weighting factor on the noise attenuation performance. Experimental results showed that the error weighting factor strategy increased attenuation of the target seats by up to 1.15dB more than in the case of the entire seat control.