Map/Navigation app that pre-downloads entire map of a region

Hey! I am looking for an app that will allow me to get full resolution imagery from google maps without the usual method where it downloads the map as you go. I have the ASUS Transformer Tablet with a wifi-only connection, and so when driving it usually does not take long for me to leave the regions of the map that have already been downloaded... and once I am on the road... there is no loading more maps... and then it is useless.

So I want something that will download the fully detailed map for an entire state, country, etc that you want. Then you can drive around it all you want without having to download imagery on the fly. Of course this would take up a bit of hard drive space, but I only need it for my week load road trip of New Zealand's South Island, which I would not mind clearing other data for. It would take very long to manually drag across an entire region to download a map and wait for it to load, and im not sure if by the end some of the other places that were loaded earlier would subsequently be deleted.

I should add that this should have GPS, road navigation functionality as well. Not just a really big picture that I can scroll around.

I feel like the best thing would a program that downloads the map you need and stores it with Google Maps app cache, so you can navigate with that.

Does anyone know of an app that can do this?