It's worth mentioning that this is one of those times smartphones with larger screens help. The Samsung Galaxy Note II I was using let me easily look at what businesses are available off exits far down the road. Even if my iPhone had been able to show me these things, it would have been tough to view them on its comparatively tiny screen (3.5 inches diagonally on my older Apple 4S, compared with the Note's 5.5 inches).
Another nice feature available on the Android, but not Google's iPhone app or Apple's software, is that the phone's screen enters a night mode when you're driving at night. The background turns dark, so it's not as distracting.
One drawback with Android phones: They have a hard time finding enough juice, even when plugged into the car's charger. In fact, the HTC Droid DNA I was using gave me two warnings that my energy usage was outpacing the power going into my phone. A colleague had a similar problem using two other Android phones. By contrast, the iPhone seems to stay fully charged if you plug it in.
Of course, I could shut one Android phone down while I use another, but this probably isn't an option for most people.After we got to Michigan, the phones also proved useful for quick little trips in town. That included a last-minute trip to a Toys 'R Us that I couldn't quite remember the location of. I also got to a restaurant that was slightly off the beaten path. Bottom line is that when you're on the road, all three programs will probably get you where you're going. They offer clear maps and audible instructions that are easy to understand. They give you the directions you need with plenty of time to make turns and get in the appropriate lane of traffic. And when you inevitably do miss a turn or highway exit, they are quick to recalculate your route.