To be 100% protected you'd have to never go out in public (remember car jackings are a thing where they rip you right out of the driver seat at a red light).
So we play the numbers/ percentages game and protect ourself from the most common places cars are stolen from,,,,, and according to the ever helpful Google AI bot, that's our own residence.
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I have a small of fleet of vehicles (side effect of being a gear head and having two driving age children still living with us). All the expensive cars (aka, not the kid's cars) are parked either in a garage or behind a locked gate.
Does that make them impervious to being stolen, no of course not, just makes it more annoying for the would be theft so that they move on to an easier target (the whole you don't have to out run the bear, you just have to outrun the slowest person in the group to not get eaten concept).
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