Perhaps I can help to muddy the waters a bit. I lived in California for the better part of four decades and used to have to deal with their silly firearms laws.
I used to keep an unloaded firearm in a locked container, specifically one of the small steel lockboxes with the steel cable that work well under the driver's seat. I usually used a semi-auto with magazines of 10 rounds or fewer. And would keep an empty magazine in the pistol and a loaded magazine hidden somewhere else in the car. (more on that later)
The locked box usually just stayed under the seat, but if the situation warranted it when traveling through iffy areas, I would either keep the steel box on the passenger seat or under my legs on the front floor with the box locked, but with the key inserted into the lock. This way it was technically legally locked but was easy to access quickly. And also easy to quickly remove the key if necessary.
Now to the loaded magazine part - I used to keep a printed copy of the relevant California Penal Code in my glove compartment concerning unloaded firearms being transported in cars and the relevant part was highlighted in yellow. To wit, page 31 of this -
http://ag.ca.gov/firearms/forms/pdf/Cfl2007.pdf -
"It is unlawful to carry a loaded firearm on one’s person or in a vehicle while in any public place, on any public street, or in any place where it is unlawful to discharge a firearm.(Penal Code § 12031(a)(1).)"
"A firearm is deemed loaded when there is a live cartridge or shell in, or attached in any manner to, the firearm, including, but not limited to, the firing chamber, magazine, or clip thereof
attached to the firearm. A muzzle-loading firearm is deemed loaded when it is capped or primed and has a powder charge and ball or shot in the barrel or cylinder. (Penal Code § 12031(g).)"
"For the purposes of Penal Code section 12023 (commission or attempted commission of a felony while armed with a loaded firearm), a firearm is deemed loaded when both the firearm and the unexpended ammunition capable of being discharged from the firearm are in the immediate possession of the same person."
"It is unlawful for the driver of any motor vehicle, or the owner of any motor vehicle irrespective of whether the owner is occupying the vehicle, to knowingly permit any person to carry a loaded firearm in the vehicle in violation of Penal Code section 12031, or Fish and Game Code section 2006. (Penal Code § 12034.) Also, see “Other Prohibited Acts,” page 49."
"In order to determine whether a firearm is loaded, peace officers are authorized to examine any firearm carried by anyone on his or her person or in a vehicle while in any public place, on any public street, or in any prohibited area of an unincorporated territory. Refusal to allow a peace officer to inspect a firearm pursuant to these provisions is, in itself, grounds for arrest. (Penal Code § 12031(e).)"
Notice the relevant parts from above - "a live cartridge or shell in, or attached in any manner to, the firearm," "magazine ... attached to the firearm," "unexpended ammunition capable of being discharged from the firearm," - a loaded magazine hidden somewhere else in the car does not meet any of those requirements. But the "but not limited to" part tends to make it a little more vague.
Also the part about - "when both the firearm and the unexpended ammunition capable of being discharged from the firearm are in the immediate possession of the same person." - but this is in connection with an attempt to commit a felony... which I was not.
So a law officer might not be up on the nuances of the penal code, which is why I kept a copy in the car. (Also judges can have different interpretations.) But when a law officer sees that an individual has a copy of the penal code in his car and will politely give him instruction on it, he's more likely to get the notion that he'll be spending time in court testifying and could be more inclined to pass on this individual.
Be that as it may, I was never once stopped and asked about firearms in my car. I did get a ticket once back in the 80s for 35 in a 25, but the subject was never broached.
I learned a lot about California firearms nuisances on Calguns.net and specifically from an individual on there who was quite up to speed on California laws and their vagueness by the forum name of "Librarian," who is a super moderator.
calguns.net in case you want to further research this. I haven't done any in the last several years since I now live in Arizona, the free world.