A dedicated car GPS RNS in VW.
However, as I refuse to pay the crazy GPS rental fees abroad, I use a TomTom XXL sat nav.
I am looking to use an android tablet but my confidence isn't high on that after trying to figure out which is the most stable and comprehensive android Sat Nav app out there from the forums here (complicated by maybe wanting to try my TomTom XXL gps and something else like iGo on the tablet together fill in any gaps in both).