According to priuschat you can leave your prius “idling” with light duty power draws (a small lcd tv and a fan) for about 7 days on a full tank of gas.
Also I think on the prius the starter motor-generator is also the one that bleeds excess engine power to charge the battery, but I’m not 100% sure on that one.
Anybody else starting to suspect that spez might have committed a teeny tiny bit of investor fraud?