Interesting thread.
I just did a quick test and noticed that when I used my Android Smartphone and asked for the phone number of two local Ford Dealerships the Google results provided the local phone number with Area Code.
I did the same search via my laptop and Google provided me with links to the Dealerships' webpages - both of which only offered toll free numbers as you pointed out.
Concerning the use of toll free numbers, I'm almost certain the stores are using them so they can track what is driving phone traffic to their stores.
(e.g. One toll free number for print advertising, another for direct mail, another for the dealership website, etc.)