I'd welcome any suggestions on where to go next - it's a bit of a fire-and-forget side project, but I'd still like to get it as good as possible before I leave it to stew for 2013.
1) get a few links. google will likely send you more traffic if they see others linking to you.
2) ask people to link to you on the site.
3) add some social buttons ("share this on facebook" and "+1 this"). Also, try to get it on pinterest. You might create a "5 car tips" image that could get shared as an image on pinterest, generating traffic and likely getting some blog links.
4) split test your adsense. use all three units, plus link units. then split test which ads work better when placed where. Think long term. 10% better RPM will add up. You probably want to add a skyscraper.
5) add links to amazon (through their affiliate program) where useful. need a tool for that? buy one here. I like to link to searches for products, rather than actual products. That way, the user sees all the available products rather than just the one you selected, and if that particular product goes away (which it might, because in a niche, you are probably linking to products sold through amazon by others - and they can change often - or be out of stock).
6) add content occasionally. google likes "fresh" content. changing things around, adding new articles, etc. will help you over the long term.
7) tailor your html titles to describe the content, and don't have "how a car works" in every page. It makes sense, but you really want to tell google what's there, and adding the site-wide keywords might dilute the message.
EDIT: And btw, eBooks are my thing, so you really should listen and do it. "The Classic Back in Print for the Tablet (or iPad) Age."
I'd take your first few $15 and reinvest it by getting someone on oDesk to go through and fix stuff.
* First section I looked at was 'Brakes'. First article is about the windscreen washer. Then there's two articles called "Adjusting the Brakes /1" and "... /2". Why two?
* In the first there's one massive unreadable paragraph. In the second there's paragraph-length titles.
* I'd also look at getting your oDeskers to put the images in interesting places within the text.
At the moment it feels like an OCR dump of a book rather than the amazingly useful website it could be (and thus it feels like an SEO AdSense site).
The truth is, having scanned and OCRed it all, I'm sick of the sight of it for the time being so I haven't proofread it. I will get onto this. And your suggestion about moving the images around is a great one - I'm conscious that these pictures are lovely but I'm not displaying them well at all.
You could also see if it would be good as a source for citations in the relevant wikipedia articles, but that's a whole project in itself probably.
I'm hesitant to go adding my site as a citation - it's a good idea but it just seems a bit black-hat for me. Hopefully it's something that might happen organically though.
I mentioned it because your site seems like a genuinely good source that WP would be happy to use, making it a win-win. Don't try and use wikipedia for pagerank boys and girls.
But I'm basing that only rumour and supposition so certainly don't take it as truth.
I have no data of my own to support the above. Theory says that "nofollow" will not help is SEO.
Why though? I think the manual "semantic web markup" is a failed promise, more than anything.
The idea was flawed from the start for general web use (for one, you cannot trust content providers to add relevant semantic info, either because it's in their interest NOT to do so --e.g SEO spam--, or because they are not competent or lazy). Plus, the tools never materialised.
It's another case of "worse is better".
For example: http://www.howacarworks.com/articles/removing-the-oil-pump
"On en gines where" " If yot are in "
No wonder Google doesn't pick it up.
Something that shows suggestions/auto-completions by matching the input against article titles.