There are really two contradictory answers to this question and I tend to agree with everyone so far, so I guess that puts me on some proverbial fence. I don't mind. I get a more clear picture of the landscape from this vantage.
On one hand, dealers and vendors should strive to source traffic, leads, and sales as well as possible. Then, there are the intangibles. For example, what's the value of an impression? Is it worth it to get your brand message in front of people by paying for Twitter ads? Some would say that it's worthless, even if you target the local area, because people don't go to Twitter to buy cars. Then again, they don't turn on the television in order to buy cars, either, yet many dealers see bumps in sales when they have commercials running. Is $2 a day in Twitter promotion too much in order to get the brand in front of thousands?
On the other hand, people often say that "numbers don't lie". However, interpretations of the numbers can be misleading. In essence, a savvy dealer will be guided by the numbers but won't necessarily let them overrule the results. Quick story to illustrate this...
A client was looking at their SEO, PPC, and social results for their second month with us. The numbers were pretty strong but not overwhelming. Yes, there were major gains in traffic, but they were not seeing much of an increase in leads. However, March was a record breaking month in sales for the store. Was that us? Was that a better television ad that resonated with more people? Was it just the fowl February weather that caused a bottleneck that was happily released in March? They don't know. We don't know. All we can do is look at the trends and continue to drive more traffic. All they can do is dig deeply into the numbers and try to see if our efforts are worth the price.
Bottom line is that it's often hard to attribute success or failure to individual sources and circumstances. As Joe said, if a buyer is exposed to 20 different points of possible interaction with the dealership, which one compelled them to come in and buy? Which 1, 2, or 10 efforts out of the 20 worked the best and made the difference? I'm not sure if there's a pure form answer to the question, which is why I'll happily remain perched on my fence.
