Mitchell- before I go look, I'm gonna be lazy and ask- what's your call to action in your ads/batch tagline? Check mine out here:
2006 Mini Cooper, $15,793 - Cars.com
Whenever I hit them with the same thing about traffic, I get the same answer. However it does seem to be something I can correct- whether it be change up my batch tagline or have them change the number- I get quite a few wrong number callers from both Cars and AutoTrader. Yes, my quantity of "leads" has decrease as well, yet my quality that actually contact the dealership thru email or phone has really improved. They are more immediate funnel than 30+ days out like they used to be.
One thing that's been discussed in the Memphis market is the fact that more and more the people are just coming in- they are printing maps, they are printing the details pages and the vehicle is selling within 3 days of whomever printing those off- and I'll see someone sourced as just "Internet- dealership website"...or they say some point during the deal- "well when I saw it online, it was priced at..."- hence the tagline I have...and lots of times we get they really "don't remember where online", or "it was a relative that did the search for them and they were just on the internet, don't bug me with details" attitude...
Hope maybe re-writing your batch tagline helps- I did earlier in the month and it generated traffic- don't know if it's truly the correlation, yet sometimes it's the real little things.