I wonder how this would play out as a constitutional challenge...the technology like that in Kyllo isn't regularly available...yet we're not talking about a person's home here either.
Well, the Fourth Amendment question isn't about whether or not it's in a person's home or not - it's about a reasonable expectation of privacy. Your personal data on your devices isn't something that is publicly accessible, so an expectation of privacy would be reasonable in regards to it.
And arguably you have a greater expectation of privacy in your home compared to your car. The real question is, like Kyllo, is the technology the police are using to lift the data commonly available to the public. If it is, then you wouldn't have a reasonable expectation of privacy if its so friggin easy to obtain the data just by being near the phone...if on the other hand, this technology like the thermal imaging in Kyllo isn't commonly available, then you have a reasonable expectation of privacy.