I drive a lot of miles, so statistically it's likely that at some point I'll be involved in a collision. In all my earlier cars, I've fitted a dashcam so that I can show whether or not (hopefully the latter) I was at fault when that day arrives.
Having recently changed car, I once again need to install the dashcam. The cam itself is a Nextbase 412G and simply clips to it's mount (stuck to the windscreen, with one of these adhesive mounts).
This documentation details how to install the Nextbase Dashcam Hardwire kit into a 2010 Saab 9-3 Saloon. It should also apply to most other years and variants of the 9-3 (and, to some extent, things like the Vauxhall Vectra).