exupero's blog

Driving fast but not fastest

In the previous post we explored how to choose a speed to minimize how often we pass another car or get passed. One final question I've pondered is how fast I can drive without being the fastest car in my vicinity.

For example, with the simulated traffic used in the previous post, driving the average speed has faster drivers nearby for most of the trip:


What's the fastest one can drive while still having someone faster nearby for, say, two-thirds of the trip? With this dataset, about three miles per hour short of the top speed:


While driving very slowly does tend to mean more cars driving faster than you in your vicinity, at certain speeds close to the global average it seems to create an absence of faster cars nearby:


As already discussed, driving about the average speed of the cars on the road may be a good way to minimize how many cars you pass and how many cars pass you, but perhaps that strategy works by maximizing your distance to other cars: being further from other cars means not as many cars faster than you in your immediate vicinity.

How to find such a speed in practice is hard to say. Probably you'll just have to watch cars around you and make sure there's always one catching up from behind or pulling ahead, and if there isn't decelerate. Of course, that sounds like even more work than trying to drive the average speed.