The batteries used, whether for a hybrid bus or a plug-in car, would have to be matched to the application. The "car" batteries we're all used to are known as starting batteries - they are designed to provide a relatively large power over a short time period and then be recharged. They are maintained in a high state of charge more or less all the time by the alternator in the car and are not really designed to go very deep into the discharged state. Draining them and then recharging them will drastically shorten their service life compared to the shallow discharge cycle they're used to and designed for.
Alternatively, deep cycle batteries can be used for plug-in type cars. These batteries are designed to go into a higher state of discharge and generally provide power at lower discharge rates relative to a starting battery. Golf cart and marine batteries are good examples of deep cycle batteries. A lot of good true (i.e. designed for >20% discharge)deep-cycle batteries exist on the market - the problem is their construction. Most still tend to be lead-acid styles and thus are quite heavy. IMO, electric vehicles won't really be feasible for everyday use (except short city commutes, not the 20 minute highway drive I do every morning) until we get the weight down.
Now, once someone figures out how to get around our problem of winter and its effect on batteries... Maybe the zinc/zinc-oxide system will overcome that?