http://www.leftlanenews.com/2006/05/...to-steal-cars/

"High-tech thieves are becoming increasingly savvy when it comes to stealing automobiles equipped with keyless entry and ignition systems. While many computer-based security systems on automobiles require some type of key — mechanical or otherwise — to start the engine, so-called ‘keyless’ setups require only the presence of a key fob to start the engine.

The expert gang suspected of stealing two of David Beckham’s BMW X5 SUVs in the last six months did so by using software programs on a laptop to wirelessly break into the car’s computer, open the doors, and start the engine. "
Be a bit less conspicuous walking around w/ a Treo instead of a laptop.