GPS - Different Day Different Route

The producers of my first GPS unit, TomTom, have recently released a new couple units (the GO 730 and GO 930) with a very interesting new feature called IQ Routes.  The feature uses data collected from other TomTom GPS units over the past year to determine the fastest route from point A to point B based on what day it is.  This could prove to be a very useful feature, although many issues could crop up such as days with heavy snow or traffic wrecks, but the more pressing issue with these units is the realization  that TomTom is not only able to track an individual GPS unit wherever it is, but is collecting and analyzing this data on an individual basis.  For privacy nuts like myself, this causes concerns as to who can access this data and how closely tied it is with a single individual.  Hypothetically speaking, if one were to register a GPS unit with its manufacturer, anyone with access to the database could track where your GPS (and presumably you) are at any given moment.

A disturbing thought to say the least.  Is my concern on this a bit much - or does the ability of GPS producers to follow units present a true privacy issue?