Anyone who has looked into it is aware that the 2008 Service Manuals are not yet available. A lot of the wiring diagrams and chassis related items are apparently the same or very similar in 2007 for non-turbo related wiring, however spending $135 twice is hard to justify. A great alternative I found is the alldata site, which is updated with service bulletins, etc and has a very easy menu for finding exactly what you are looking for. I used it for a couple of years for my Silverado, and just bought the 2007 HHR subscription. http://www.alldatadiy.com/index.html