I built a driving path containing several destination points using google maps and would like to use it in a turn-by-turn GPS navigation app such as iGo. Any existing app/s that can achieve that?
Osmand Is available on Google Play that allows navigating along a saved GPS log (in .gpx format).
You can export your Google Maps route (from maps.google.com) using http://www.elsewhere.org/journal/gmaptogpx/ to .gpx format. Push the .gpx to your phone (via bluetooth, email or USB) to /sdcard/osmand/tracks/ folder (important! Osmand only searches for .gpx files in this folder).
This is however not very straightforward and requires some steps... but I have used it for preparing motorcycle routes offline in advance for example.
In Osmand then:
Osmand is free software it's also possible to get it free of charge from f-droid.org's app store, but please support the author if you like it.
Have you heard of openstreetmap?
Openstreetmap is a croudsource map database where users create a free service to use for navigation purposes. There are many android apps available that allow you to use openstreetmap maps to display many different things. You can import a variety of different map types, as well as use different programs, such as josm, to create these maps and routes to import to your choice of android application.
You can even help by contributing new roads and updating existing information.