I don't know about values of what is stolen but one of my cousins who is a retired body shop owner in Florida always left the keys in his cars, said if it was ever stolen, less damage would likely be done to it. Most of what he had were worth way more than what he had in them.

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1991 300SE (my ride, 279,000 miles, looks almost new
1954 Cadillac (21 yo son's car, he bought when age 15)
1972 SeaBird 19 ft runabout (old but solid, slant six, Volvo sterndrive perfect condition, undergoing complete overhaul and refit)
1998 Toyota Rav4 (my sons daily driver when he is in the Continental US, PROUDLY serving in US Navy)