It won't affect you... until it does.
You know the old saying, "It's not paranoia if they're really out to get you?" This is one conspiracy that is proven to be 100% true: due to a loophole in the current laws, the feds can attach a GPS tracking device to your car and track all your movements any time they want, without needing to get one of those pesky warrants first.
The principle underlying their ability to do this is the good old "expectation of privacy." It's the same reason that an undercover private investigator is legally allowed to follow you around all day taking pictures. When you are in public going about your business, because you don't expect to be private (not the way you would in your living room with your drapes drawn) so legally, you don't.
But instead of tailing you in an unmarked car, the feds can simply attach a small GPS tracker to your car's undercarriage. Two people have discovered these devices so far. The first person Wired reported on was an Arab-American man who found the device when he took his car in to get an oil change.
The second person is the subject of the latest Wired article. Greg is a Hispanic man who found a device inside his bumper when he noticed the antenna sticking out. When he removed the device, it was later replaced by a GPS tracker inside a plastic clamshell with a powerful magnet. That one was stuck to his car's undercarriage, tucked up under the well for the spare tire.
The problem with GPS trackers from a privacy standpoint is that they track everything about your life outside your home. GPS tracking data can tell someone where you shop for groceries and how often, whether you drink and how much, if you go to the gym and how often, which church you attend and how often. A GPS tracker could uncover whether you are sneaking cigarettes, cheating on your spouse, sneaking out of work early when the boss is gone, or stopping by Baskin Robbins on the way home from the gym.
Many people's response is "Don't break the law and they won't have a reason to track you." But if this legal loophole isn't closed, consider who else can legally GPS track your car. Imagine if your employer, your spouse, your car insurance company, or your health insurance company decided to start using these devices. Legally, they can.
And maybe it's not such a bad idea to rig up one of those "mirror on a long stick" devices they use to check under cars at border crossings! Just in case.