That depends on who controls the software running on the car or phone. Determining your position via GPS does not emit any signals that can be detected; it's a purely passive process. If malicious software installed on the phone records the GPS data and later transmits it, then yes.

However, cellphones in particular do require the cellphone network to track at least which cell they're in in order to work, so in practice controlling a cellphone network gives you a pretty good idea of where all the subscribers are.

This is a big problem, and we need to figure out how to stop it if we are to enjoy the sort of freedom from government surveillance that people everywhere enjoyed since the Paleolithic until about 01998. The 20th-century results of giving too much power to governments are not promising.

Something doesn’t become a good thing just because it’s possible and/or been happening for a while.

Yes, they can.

"Reasonable" changes over time, with available technology, and with the tolerance of the public. People don't much care for "We could've stopped that murder / caught that murderer, but we didn't use the resources available."

If there's a murder on a street corner, do we expect the cops to not pull camera records from every nearby store with an outward-facing camera?