Acoustic comfort has become an essential feature with the rapid development of the electric vehicle (EV) industry. As a representative nonlinear model, Zwicker's psychoacoustic annoyance (PA) model and a series of modified ones are established to evaluate the acoustic comfort of different products. However, whether these PA models apply to the noise-induced discomfort in the EV cabin remains uncertain. We investigated the psychoacoustic metrics and subjective discomfort of the EV cabin noise running at various speeds from 10-110km/h under four typical road conditions, i.e., asphalt, concrete, gravel, and bump. Thirty subjects rated the discomfort caused by 16 noise stimuli on the standardized 0-10 point numerical scale. The correlation and partial correlation analysis confirmed that the loudness of EV cabin noise dominated, and roughness and sharpness significantly influenced the discomfort. We identified that the original Zwicker's PA model performed well in evaluating the discomfort caused by the EV cabin interior noise and proposed a modified Zwicker's PA model that would be appropriate. Keywords: Electric vehicle, Cabin noise, Psychoacoustic annoyance, Noise discomfort, Sound quality