From my seat, I found the ONLY trustworthy TRAFFIC source data would come from a survey at delivery.
Here's a couple take aways from >20,000 delivery surveys I collected over 5 yrs.
INTERNET
80% consider themselves a "frequent internet user" (more than 30 mins a day)
22% of all of my buyers used Cars.com or Autotrader at sometime.
85% of all sales were on my site prior to purchase
...and 70% of these went to my site 3x or more
COMPETITION
43% of all buyers shopped never stopped at another store.
25% of all buyers shopped at just one other store
LOYALTY & REPUTATION
70% of all sales were to either a repeat buyer, or to someone who knew a friend or family that was a buyer.
TIME TO SALE
50% were in shopping 3 months or longer
TRADITIONAL AD PERFORMANCE
90% of all buyers saw my TV ads, but...
25% found these ads helpful
http://forum.dealerrefresh.com/f43/survey-delivery-road-map-your-store-3751.html#post32318
