If you know extremely little, HowStuffWorks.com is a good place to start.
If you are beyond that stage, another great site that I kinda stumbled across is
http://craig.backfire.ca/pages/autos. The site has some pretty good techincal info in it covering a range of topics from engines to aerodynamics.
There is also wikipedia. Even if the info on the main page isn't the greatest, you can go down to the bottom & find what the sources they used are and continue from there.
I don't know of any auto-eng books for laymen, most of my automotive books are history type, except for my copy of the SAE handbook but that is super technical -written by (German) engineers for other engineers.