Altough the map lacks routing (what can you expect from a free official Garmin map?), the OSM road network is still in the map data and can made visible by changing the typ file (use gmaptool to extract it from the img). In this example, https://www.dropbox.com/s/o6c1doj3oqf8uhi/innsbruck.jpg I removed some typ definitions (to show the normal layout of major roads) and made the cycleways red ;-) nwillink wrote:

Interestingly , the typ header suggests active routing - but there isn't any. Also, the typ file includes spurious data relating to hotels etc normally bundled with nuvi typ files. It also contains 'extra POIs' , ie ski lifts, which unusually are clearly visible. There doesn't seem to be any routing other than 'direc't ! As there are no active routing 'lines' in the typ file one can presume there is no activity called 'skiing' ...