In this paper, we investigate the auxiliary vehicle positioning system and localization method for intelligent transportation systems, as a supplement to the Global Navigation Satellite System which is prone to large positioning deviations and even failures in occluded scenes such as urban canyons and tunnels. The time modulated antenna arrays are first introduced into the positioning system, avoiding mutual coupling between antennas and greatly reducing the hardware cost of the vehicle terminal. The auxiliary positioning framework for the smart vehicle is advocated in conjunction with existing radio frequency signals. To take full advantage of the multiple auxiliary sources around the road net, Doppler shifts embedded into the received signals are unearthed, and a smoothed block sparse reconstruction is developed for directly locating the vehicle, providing significant enhancements of degrees of freedom and the localization accuracy. Additionally, the proposed direct localization method is robust to multichannel gain and phase mismatch in practice, and the array perturbations can be estimated and compensated without any calibration source. Extensive simulation results corroborate that the proposed system and method achieves superior localization accuracy (approximately 0.22 m error at SNR of 10 dB), outperforming its state-of-the-art counterparts.