Most useful app I initially installed the free version on my old Nexus 4 to use as a replacement speedometer for my truck (stock speedo is broken). Liked it so much I just used it on a 20 hour road trip for my car (whose stock speedo does work). Made watching and maintaining my speed so much easier, I actually liked using it better than using cruise control. Would have been wrong to not buy the paid version. (Plus, it just looks really cool.) Highly Recommend.