If I’m planing a trip with a car let’s say from Porto (Portugal) to Riga (Latvia), can I export only maps for the route I planned from Porto to Riga and additionally the destination city.
I would want the map for planed road ± 1 km of surrounding details with Gas stations, rest places, dining …
Now I can export only square maps of only 90% of whole Europe.
Using http://extract.bbbike.org you can extract a polygon shape of the map route required. I think that these maps are specially suited to bicycles but may be fine for car navigation too.
Using http://garmin.openstreetmap.nl you can use manual tile selection and choose just the tiles that cover your route.
The only other option i know of is to download the .osm map data bit by bit along the narrow route, save it to your hard drive using josm and then use http://www.mkgmap.org.uk to convert the .osm file to garmin format for your gps.