You are correct however, under the 4th amendment vehicle clause, police can search your vehicle without a warrant. Only need probable cause. Does that mean they can pull your computer history seeing how fast you were going, Were you on your phone, Even pull video camera footage, yes it sure does. Meaning that data your car has stored can and will incriminate you. Utah has enacted a law against police gathering location data without warrant but that's about it for now. Everything else is free game. Do I believe this is a 5th amendment issue as well as a 4th. Yep. But we'll see. It'll probably take a politician phone records getting seized from their car or going to prison because GPS location said they were going way too fast to change this.
Now, Can the police go through your cell phone without a warrant? Nope. Especiallyif locked. Many do or will try to trick you into letting them but that's theirs and your bad. Should cars data be protected like phones. Yes. But current. Nope, not at all.