I can't find any pictures of Packards or anything else with an exposed gas tank as late as the 1920s, except for a few racing cars. Indeed, that whole trunk/tank arrangement is rather odd looking. I've got a feeling that this is custom coachwork, either in its entirety or at least from the passenger compartment back. Given the location - a couple of miles south of Hollywood and east of Beverly Hills - I'd guess that custom cars were relatively common in that area in the 1920s. Something about the car (the apparent lack of any provision for a top) has to me a very specific Southern California feel to it.