That additional data is specific for mobile GM and mobile GM uses custom communication protocol designed especially for it, so I doubt there is any tool, which is able to download that data. I have enough knowledge to write such tool, no problem, but I don't want to. It would be too... rude. Maybe this is ridiculous, but for me using some simple HTTP protocol is just using it, but using custom, binary protocol is like saying: "Hey, you guys! Your complicated protocol can't stop me, I've just hacked it!". Even if this protocol most probably wasn't created for security, but efficiency.
@n0b0: Concerning data costs, in Israel, one of the Internet (not cellular!) providers came up with the following neat idea. When you're going abroad, you can rent a cellular modem from them, which works abroad, and the price is much more reasonable than roaming with your phone (I don't remember the exact figures, but it's something like $100 for month, incl. reasonable traffic per day and the modem rental fees). Check with your Internet providers (and maybe cellular providers, as well) - maybe they offer something similar.