[dogma1138]

Yes, the police doesn't need a warrant to tail you, question any one you speak too, or even use public systems to gain information on you, heck they technically don't even need in some cases a warrant to say get your phone records or any other record from any other person or company (they do need consent which is more often than not the actual reason behind a warrant being filed in the first place as it solves that issue).

They may not however tamper with your personal property.

If you do not own the car and say it's a company car the police might also not need a warrant to put a GPS tracker on it if they get consent from your employer, this might also cover rental cars (not sure about leases).