A family of compact-size wideband antennas with controllable traits and directivity is introduced in this paper for efficient wireless communications in the automotive regime. The proposed radiators are optimized in terms of unhindered EMC function, even when other vehicle electronic systems are involved. Moreover, to attain reliable designs, a generalized explicit method of scalable accuracy is developed. The featured technique combines a finite-volume time-domain and a pseudo-spectral time-domain approach which divide the domain into manageable regions. This concept leads to very accurate and economical discrete models, free of lattice artifacts. Results, compared with reference or measurement data, reveal the benefits of the miniaturized antennas and substantiate their potential applicability.