Electron -spin-resonance (ESR) spectra of the VCl4 molecule were observed at low concentrations at 2-4 K in solid H-2, D-2, Ne, and Ar. As previously observed in other matrixes, the spectra of an axial molecule were obtained in H-2, D-2, and Ne, indicative of a Jahn-Teller (JT) distorted molecule with compressed tetrahedral D-2d symmetry. However, in argon, a composite of an axial and a near-isotropic spectrum was observed, and annealing yielded only the isotropic at 4 K. This surprising result is discussed relative to JT dynamic vibronic interaction. Photolysis of VCl4 in H-2 (and D-2) matrixes yielded a new spectrum assigned to VH4 (or VD4), indicating that the tetrahydride is also a JT-distorted E-2 ground-state molecule, in accord with earlier ab initio theory.