That question came up at a family gathering after my cousin bought a fairly recent Ford. He was confident that all the newer security features made his car practically impossible to steal, but a conversation with a mechanic gave him a more balanced view. Modern vehicles have better encryption, updated immobilizers, and more advanced key systems, although no technology is completely immune to electronic attacks. I also found it interesting how much security equipment varies between manufacturers and model years. For anyone curious about the subject, this page discussing the fantom grabber and vehicle security technology provides some context about the devices involved. My cousin eventually added a few extra precautions, including keeping his keys away from exterior walls. It seems that combining factory protection with sensible everyday habits is a reasonable approach.