Should or can I (car) wax my frame?
Using car wax on your frame could certainly help protect it over time, though storing it indoors is much more important so that all of the components are protected from the weather.

There are bike specific products like Pedro's Bike Lust but if you don't want to go that direction you should be just fine with any auto wax. In the past I have heard of people using furniture polish as well to give the bike that just out of the shop shine.

You will want to avoid the harsher products that contain aggressive abrasives like rubbing compounds, especially if you have carbon portions of your frame, as these will remove the clear-coat and can lead to damage or failure.