I don't know about MOTOR although I believe that name has been around for years in repair information for shops. The site has a few references to ALLDATA though, which is another such repair info system for shops. ALLDATA has a DIY subscription service that can give you repair info specific to your car:
ALLDATAdiy.com Leading Source of Factory Automotive Repair Information
It's not perfect, in my experience, but it has helped me. It's as adequate as some other repair manuals I've seen, although I haven't bought a paper repair manual specific to my own car.
I've also found good tips by just googling and finding results that were in brand and sometimes model-specific online forums. Some people post really good detailed how-tos with pics and everything. I was able to better understand the power antenna mast replacement and the hatch actuator replacement on my Integra thanks to helpful folks who shared their own experiences online.
None of this lends itself to general reading about generic auto maintenance though. These are things to go to when you have a specific repair you're trying to complete.