Yes. The only time I've had a car broken into I had left a suit jacket on a hanger next to a rear window. Perhaps they thought the jacket might have had a wallet in it. They didn't find my emergency cache of 'petrol money' I keep in my car in case I forget or lose my wallet and need to fill up. This was a hotel car park in the UK town of Bedford.

If you do put stuff in the boot (trunk) you should do this before you park, otherwise it is a dead giveaway that you are hiding something valuable.