Yep ... as far as the "V" designation went. The HiV's and early cars had TRAINLINE 600 volts which caused some interesting problems, not the least of which was "gapping" a third rail where if a section had the power turned off, it was possible for a HiV train to "bridge" the gap and REPOWER the closed section. In fact there were special signals to stop a train from doing that before it bridged them. There was also concerns about 600 volts in the cabinet.
Wisdom dictated that using the battery voltage to operate the relays and contactors under car and passing the 36 volts trainline was a lot smarter and a lot safer and all "modern" subway cars from the R1's on up had "Lo V" control. The IRT car classes went by name such as "steinway, gibbs, roof deck, flivver" and so on. There's others here who can provide a much greater degree of detail as there were many MAJOR differences between each of the car classes and many could not be mixed with the others. On the 3rd Avenue El in the Bronx, the WF cars were mixed with LoV's and that worked.