I always appreciate the varied input on all topics here at PF and it keeps me thinking of things I might not have thought of before. however sometimes I see issues taken to extremes that don't fit with a balanced life of risk, common threats and realistic threat assessment. In this case it seems to be headed that way. There will always be locations that are NPE with serious legal repercussions for violating them. The need to go to these places varies as well as the time or frequency of going to one. Regardless of the circumstances it is important to do a reasonable job of securing a firearm when going to a NPE where secure storage is not provided. This seems to be best handled by a secure method in a vehicle. That is the main gist of what is being discussed or queried by the OP as well as technique for doing so and associated equipment.
Some ways are more secure than others or easier to do safely and with less complications of doing so and upon returning to the vehicle reversing the process. I personally like the lockbox with cable because it also is a convenient way to use the same thing for air travel and secure it to my suitcase, storage in hotel where safe is not available,storage in any vehicle I use whether it is a rental or one of my several vehicles. This is not as strong as a dedicated lockbox mounted to the vehicle as others have suggested. I get that and accept the risk. However in my entire career in LE near a major metro high crime area I have never heard of a thief having tools capable of quickly removing a large torx bit used to attach the seat to almost all the cars I have used this method in. I also haven't heard of any carrying bolt cutters capable of cutting the size cable these boxes have. Both are not impossible and could be accomplished without crazy time,money or equipment constraints. But they are very unlikely to be a real factor. If anyone has a real example where this has occurred I am happy to change my opinion on the issue.
I use the same method as Revolver Rob and it allows me to stay in the vehicle when taking off or putting on the gun and/or I can drive away and do the same process elsewhere if there is any doubt to safely accomplishing the task without drawing undue attention. No need to go to the trunk, be out in the rain or other weather or be out of the car and more visible or approachable with back turned etc. The risk of car theft is always a problem but with modern chip/key technology and electronic counter measures it is less likely than in years past. It also still can and does happen. The risk is balanced with having a gun to and from the NPE location. Is anyone suggesting a person not carry to and from and associated errands or activities because they know or may encounter a NPE environment? I can understand if it is a known NPE regularly traveled to with extended stay in the NPE such as a workplace. Maybe not carrying is the more reasonable choice or as suggested by GardoneVT maybe making the gun non functional with slide or other field stripped part is reasonable. However keep in mind the associated risk in more complex, longer process of doing so and how that factors into time being vulnerable to attack while focused on removing gun, field stripping, placing part(s) in lock containing maybe in the trunk while outside in the rain with people in the area. Is it faster,easier and safer to jsut draw the firearm and place it in a safebox under the passenger seat?
I am not faulting anyone for pointing out risk associated with any method used to secure a firearm when going to a NPE. I just see some comments taking the risk vs benefits to levels that in my experience seem more unreasonable than not having some access to a firearm by use of a secure box attached to a vehicle. I didn't look for it but I wonder how many firearms are stolen from vehicle vs homes and if stolen from a vehicle how many were ever attempted to be secured at all or beyond a locked glovebox or console? I would wager a guess that 95%+ are not properly secured in a vehicle with probably 80% or more taken from the home vs a vehicle. Again if i'm wrong I am humble enough to retract my statement.