(Inspired by [neelandan]'s "faux progress odometer")
This gives you something interesting to look at during a traffic jam, and it's real data.
It's a digital dashboard display that shows:
- average speed of your lane
- average speeds of the lanes to your left and your right
(both averages are taken over a broad period, longer than you can mentally sense; say over the last 15 minutes, starting from when your car first reaches traffic jam speed (5 mph or less))
- number of cars you've passed
- number of cars that've passed you
- Rate of passing other cars (e.g. you pass one car per 30 seconds, or you get passed by one car per 22 seconds)
There would have to be a camera mounted on the car's roof or sides in order to collect this data. A memory of, say, 200 cars or 30 minutes of time, would be needed to make sure you don't double-count a car that passes you, then you pass, and then passes you again.