We have been posting on behalf of dealers for a long time and have a LOT of data. I believe when done correctly they can provide a lot of value.
The data below is from a dealer who has been a client for a long time, so there is a lot of history. This is a three month look back on organic traffic that visited the blog.
Here you can see the total visits and then I filtered down to US and the immediate states surrounding this store. While the numbers drop pretty significantly, it's still a decent number of people. @craigh mentioned session duration, and it is low, but you have to be careful using that metric because it always factors in a zero when calculating that average. You will also notice the bounce rate is terrible.
If you look page views, you can learn a little more. The bounce rate is high because the users are really only interested in whats on that page, you can see that the average time on page is telling us the content is actually being read by the users. I'm not advocating that Avg Time on Page is a perfect metric, but it gives better insight than Avg Session Duration.
Last thing to look at is content. You can see from above that vehicle based content does perform well, particularly comparisons within the brand. We've always felt like this was a great opportunity because someone has decided they want a particular make or model, just trying to pick which one. Also, there is a lot more search volume on older cars.
Below is showing you that local community content also performs pretty well. We try to write about local businesses, people, events, etc. and we share that on social. We also will email, @ mention and tag the local businesses and people we write about. This is not only a good thing to do as a community business, we sometimes can earn backlinks to the content.
So to echo what @Alex Snyder, @Alexander Lau and others have said, the relevancy of the content really matters, but you also have to make sure you are promoting and sometimes even updating old content. I also recommend creating custom retargeting audiences based on this traffic, being aware that you may want to even exclude some.
I can't say that I'm opposed to the idea of having a dealer blog.
On a consumer level, I'd love to see more Video-Blog (vlog) type videos by dealerships and their sales teams. Not only would vlogs give an up close and personal view of a dealers operations, it'll make the car buying experience with said dealer much less frightening/intimidating.
Nothing makes a person more comfortable than knowing MORE about the people you intent to do business with!
I completely agree with this. More and more people are viewing YouTube videos to compare vehicles, look at features, specs, and compare across different models between brands. I think it's more impressive when you see an actual dealership post videos on specific models and its features. There are a good number of people who still read, but the number of users on mobile devices researching new vehicles is doubling every year. I was just researching yesterday on a few models of a car on YouTube and only found maybe one per model that actually had a long (10+ minutes) video with a test drive and a detailed description. I think these videos give an opportunity for great exposure for dealerships!