Why dont you just obey the fucking traffic laws?
Also, I honestly think thats something you'd get better from Android or maybe google for iphone.
Standalone navigators are shit by comparison.
The best Android nav app imho isn't anywhere close to a good stand alone GPS. Sygic on Android's the best nav app by far, and it's still not as good as my Tom Tom.
Google Navigation has done as well if not better than my garmin/tom tom. Only reason I would use a standalone is if I was in an area without service.