What's the difference between common rail and mechanical injection diesels?

Diesel engines rely on different types of fuel injection. Mechanical was used early on, but common rail became more popular ...
Autoblog

VW says goodbye to TDI, hello to common-rail

VW will be dumping its line of TDI diesels by 2007 and switching to a common-rail design for all of its oil-burners, with annual production of the new engines totaling over 2 million units. This ...