The vibrational structure seen in photoinduced Rydberg ionization spectra of the B E-2(2g) state of benzene cation (C6H6+ and C6D6+) has been analyzed by fitting the vibrational patterns to energy levels derived from multimode Jahn-Teller calculations. Most of the structure can be ascribed to various combinations of modes 6 and 16, with minor contributions from 4, 17, and 18 (using Wilson's numbering convention). In qualitative agreement with parameters derived from electronic structure calculations, the linear coupling parameter for mode 6 is very large (D=1.39 in C6H6+ and 1.28 in C6D6+). This raises questions about certain angular momentum selection rules in the classical Jahn-Teller model.