I use race chrono a lot. It's supposed to be for the track but I use it on the road too - plots your route on a map or 'race track', shows you the exact route on google maps and provides a telemetry graph to show your speed over time against the map - ie you can see your corner speeds, 0-60, save any good runs you do, and even more practically on the road to time and plot the exact routes you take which is great for planning drives or even as I use it, the best ways to work.
I also use Digihud as a good heads up at night and usually after passing a hidden speed camera and not being sure what my 'real' speed is :lol: