Very true... I just don't get thieves.
I have this sign on the Dash of my BMW when I park it anywhere...and mind you I don't have it all fixed up like some people do to their cars... its just a normal White M-Sport with 35% Tint...anyway on the 8x11 printed paper it says, "I'd rather you not break a window nor wreck the key hole, doors unlocked" Sure they might take my FastTrack or the spare change, heck sometimes I wish they'd steal the whole car and take it to Mexico so I can claim it on my insurance lol... Maybe I'll leave the keys in it one day and see if it happens haha
I like that.
I may have to copy you and put that sign in the window of my ~20 yr-old Camry.
I use the GPS on my phone and an old 4th-gen 32GB iPod Touch for music, with a wired adapter that goes into the cassette deck so I can keep the stock radio in there and not have to worry about someone trying to jack the $1500 NAV system from the console that was an option at the time...
Both devices adhere to the dash via neodymium magnets and there is no obvious indication of what the magnets are for, just a black circle.
Nobody wants the old head unit that is there now.
When I leave the car, I just stuff the iPod into my carry-bag and put the cassette adapter and iPod power cord in the center console. If they want them, they can have them, as they are like $7 on Amazon or $5 at FiveBelow.
Nothing else of value is left in the car save for an umbrella, a flashlight, tire pressure gauge, and some road flares (all save for the umbrella are stored with the spare tire), unless they want to steal the spare tire and nice scissor-jack, which are all under the trunk floor, and the spare tire is bolted down with security bolts as the lug nuts to deter thieves.
I also usually have a ton of heavy stuff in the trunk, and all of it has to be removed to get the trunk floor out, and not something that can be done in a minute or less...but if they want the car, they can have it.
I'll just get another.