I use a Garmin 705 which is actually my Bicycle GPS. It has a small screen which makes a little hard to see but it is easy to mount out of the way and takes up very little room. Being a cycling computer it has some fun features not normally found on a car based unit. First off it is waterproof. It also has options to track top speed, avg speed, elevation, heart rate...etc..... It has a full color screen and will allow you to route using back roads only.