Navigation accuracy

[euro5525]

Hey guys?

My navi is sucks.
I have two other navi( one of them is iphone-navigon). Those are only $50~$100.
Navi on my X5 35i premium is so expensive but it isn’t really accurate.
e.g. looks like only 20~30 feet left to make turn but navi still show 100~200 feet to make turn.
My other cheaper navi is much much more accurate.
Is it possible to fix it or modify?
I lost way so many times because navi showed making turn in 100fts. So I prepaired to turn and assumed the how far. But 10~20 fts later, car navi recalculate route. It’s really suck.

Does anybody have any idea how to fix accuracy?