Our older Garmin used for truckers, will route you around AND alert you to the upcoming, possible issues. Found on Amazon much cheaper than in stores. (If you read the reviews on Amazon. They will give you users' thoughts).
Ours was cheaper because....it was "last years' model"!
Our "on-board" GPS in the dash will give elevations and misc. info of your current position. Have not been able to find any way on the in dash to find altitude. And no option to switch to trucker use like the portable Garmin.
We use both because in-dash cannot be programmed during driving. Safety first.