I recently discovered “How a Car Works.” I love this site. It’s a beautiful illustrated guide to… wait for it… how a car works. The site boasts 287 articles and 2232 illustrations. The illustrations are beautiful and the explanations are crystal clear. For example, to the left we have an illustration of the compression stroke of an engine. The authors have also created an iOS app, which I haven’t yet tried, but which looks great.
One nice feature is the popups over various terms, providing instant definitions. Someone put a ton of work into the site. Recommended to car enthusiasts or kids interested in learning more about the automobile internals. Check it out: http://www.howacarworks.com/