So many keywords, so many visitors

What is particularly surprising about the thunderous success of Name That Car! is that I've done nothing, beyond posting regular puzzler photographs, to draw people like you to the site.
Now you know, of course, about the various techniques and tricks that blogs and other websites can employ to increase traffic. The goal, always, is to improve the site's ranking in search engine results, so that people will see it high on the list -- preferably on the first page, even better, among the first few results -- of whatever it is they are looking for.
The search engines send out "web crawlers," or automatic programs that methodically comb through Internet addresses and their associated websites, recording the information they come across for storage in massive databases. Then when someone goes to Google or another engine looking for, say, "1964 Oldsmobile Fiesta," the engine will review its collected data and tell the searcher that that phrase exists on Name That Car! (plus 27,399 other places, as of this writing, per Google).
But the content of a site doesn't give the search engine any clue about how useful or credible the site might be. To determine this, the search providers seek indications of the site's popularity, or the approval it gets from other users. A common way to do this is by counting the number of hyperlinks (links, for short), that connect the site to others. Links to your page carry the most weight; links from your page won't help your score, though search engine-watchers contend that keywords in links on your page get more attention than the same keywords not in links.
Naturally, since this is commonly known, it means that people trying to boost their site's ranking tend to scatter links to their website like confetti through forums, blog comment features, anywhere they can squeeze them in.
There are many other ways to increase traffic. You can get gizmos that pick out key words and repeat them in a way more likely to catch the attention of web crawlers. If you have a blog, you can list it with services such as Technorati that rank sites by how often other bloggers are visiting them. Makes sense mathematically, though it also could seem like a dog chasing its tail.
You can get hidden programs that count the number of visitors, give you a pretty good indication of where they live (or even where they work), and better yet, tell you what search terms they used to find you and what content on your site they were most interested in. Confession: I do use such a program, but only to allow me to quantify Name That Car!'s spectacular popularity.
You can sign up to have the search engine place ads on your site. Will that improve your ranking, at least at the engine that now has a financial incentive in driving viewers to your site? Oh no, of course not.
I might sign up for ads, not to bring in more viewers -- I mean, how many more could one site want? -- but to earn a little folding cash, since my other enterprises with my Nigerian web buddies have yet to pay off.
But those other tricks? Don't need 'em, not going to do 'em. Not when I have faithful visitors such as you, who have patiently waded through this long discourse to get to the alternative answers -- one of them is correct! -- to this entry's photographic question: What the heck is this?

• 1949 Miller Cadillac hearse.
  


• 1950 Cadillac S&S hearse conversion.


• 1933 Dymaxion concept car.


• 1951 Cadillac Superior hearse-ambulance combination.