Obscurity is a useful adjunct to physical protection, but it should not be your only defence. Hiding your player under the seat is fine, but I wouldn't recommend it without also locking your doors, and preferably having a vehicle alarm and using a good safe bolted to the floor.

Making your vehicle look like it contains no valuables helps make it less of a target, but there will come a time when all the alternative targets are too daunting for the thief, and he'll have a go at yours on the off-chance. It's worthwhile slowing him down when that happens.

It's the same with computer security. Most crackers don't have as much experience with, say, AIX as they do with Linux, for example. So if you're running an AIX box, you're less likely to be attacked (all other things being equal). But that doesn't mean you should run an unauthenticated telnet daemon on some random port, just because they don't know it's there. Once they find it, your system is hosed.