I find MM to be perfectly acceptable as an in car navigation tool. The only time I've had problems is if I need to reroute, but hotspots are so easy to find (at least in my area) that's not that much of a problem unless it's a reroute I need right at that second. Otherwise you can predownload all your routes and maps before a trip and this works great! Also because of the quality of google maps its easy enough to follow a new route by eye in a pinch.