I have a mid-option BMW 316i (2013). Which means that it has an iDrive display LCD in middle of the dash, which has Bluetooth/AUX/USB and other stuff but it does not have navigation and obviously no GPS. To add nav to it, is just a matter of software change and addition of GPS receiver. Easier said than done. Is it somehow possible to do it. If yes than how.
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This may come as a surprise, but it shouldn't. The company that designed and built your vehicle did so to make a profit. That GPS / Nav system? Its a very high dollar option. It wouldn't surprise me if that option package generates $1200 USD of extra price to a demanding customer.
And then there are design and manufacturing issues. Guess what. Less is more. If you are going to manufacture something, and design and tooling costs are crazy expensive; it's way better to design things to be in common. Too many options in the manufacturing plant = the potential for screw ups and bad quality. As an example, let's look at the computer motherboard for your entertainment / HVAC Control / Navigation system. Do you want to tool up two or three of those, or just one. Obviously you are going to tool up just one. Remember tooling is crazy expensive.
I know that on the high end vehicle lines I worked at, the only difference between the navigation option and not WAS A SINGLE PARAMETER BIT SET IN SOFTWARE STORAGE at the end of the manufacturing line. And yeah, that bit location and its values was a highly secure secret from all the employees not working on that specific engineering team. And as for the GPS chip? Depends on what that costs. If its $0.10 or less it wouldn't surprise me if they just soldered that onto the board, and gave it away. Remember one quality screw up costs a lot in repair costs and reputation. (e.g. you ordered a Navigation option, and the board was missing the GPS chip, ouch.) You absolutely don't want to degrade quality.
(Note: I was curious about the price of GPS chips, so I just did a quick check... seems they are now built into bluetooth / mobile rf antenna / integrated units, and they are pretty cheap in quantity. If I had to guess, the GPS hardware is probably already there...)
You are asking for all the trade secrets on how to set that software bit.
If that every got out, it would totally corrupt the companies ability to make profit on those type of options.
Here's a hint. NOT going to happen. No way, no how. Sorry.
Have a nice day.