I have been using the L296 for a long time for the 5v stage of my power supply. This regulator (afaik) is a step down switcher though. The datasheet says that the input voltage should be designed to fall about 4v above the output voltage. You might find this tricky when the output is 12v and the input is a car battery.
The L296 is not difficult to find to buy. I would advise against not being a freeloader. Getting free "samples" just ****es the suppliers off (unless of course you are planning to actually produce a legitimate product).