What application are you using now?
Google Navigation? Something else?
I'm most definitely NOT a VZW employee. If a post answered your question, please mark it as the answer.
I found the Navigation Vehicle Dock For your M it should Keep the Screen on.. One other thing you could possibly do is set your screen not to Time out..
Here's the Link to Amazon.com They have the Nav. Doc for $24.24 plus S&H.. Here's the Link http://goo.gl/pM3MTf
Hey, if you're going to have your phone out while driving, using a mount is the safest way to go. But, you bring up a good question to supplement that point. On board with your RAZR M is the option to go to settings > display > sleep. You can set the screen timeout to a maximum of 10 minutes (please be aware that this will drain more battery as well). Regarding a third party app, you can browse popular search engines with "play store screen timeout app" to see an abundance of options, but none of which I'll be able to recommend (given they are third party apps).
Follow us on twitter @VZWSupport