Comparing resistivity data of the quasi-one-dimensional superconductors (TMTSF)2PF6 and (TMTSF)2ClO4along the least conducting c-axis and along the high conductivity a-axis as a function of temperature and pressure, a low temperature regime is observed in which a unique scattering time governs the transport along both directions of these anisotropic conductors. However, the pressure dependence of the anisotropy implies a large pressure dependence of the interlayer coupling. This is in agreement with the results of first-principles density functional theory calculations implying methyl group hyperconjugation in the TMTSF molecule. In this low temperature regime, both materials exhibit for c a temperature dependence aT+bT2. Taking into account the strong pressure dependence of the anisotropy, the T-linear c is found to correlate with the suppression of the superconducting Tc, in close analogy with a data. This work reveals the domain of existence of the three-dimensional coherent regime in the generic (TMTSF)2X phase diagram and provides further support for the correlation between T-linear resistivity and superconductivity in non-conventional superconductors. © 2011 IOP Publishing Ltd.