navigation in Boston

These aftermarket units do not integrate as well resulting in reduced accuracy because the yaw sensors, speed sensors etc require a tremendous amount of precision and integration to work accurately -

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Just curious. (And since I chose not to get the Navi, I'm not knowledgable on its features, nor the way it works.) Wouldn't the GPS care more about where the antenna is on the car rather than the unit and its yaw sensor? Also, the speed doesn't need to be "sense"d separately, does it, apart from a tie in to the speedometer? Or, does the Navi not count on the accuracy of the speedometer?

Anyone have a Navi 101 textbook?

Its basic, but if a unit is "aftermarket", I would think its calibration utilities would have to be able to make up for that somehow.... If not now, then hopefully by the time the price is right for me, anyway, if all of this is true!

Thank you for all of the info - that's helpful. So these are sensors that help fill the reception/transmission voids, so that the user has a continual flow if information. I assume you don't know which is which info (actual or derived), but the overall output leans toward being fairly accurate.

I don't expect I'll be getting an aftermarket Navi anytime soon, as even they are too much money for me to spend on something I don't think I'd use (as in really need directions) enough to make it worth it. I do think it's a cool gadget, though. Perhaps my next MDX will have one...