That's not "zen" -- it's artificial regularity. Zen would be driving at what feels like a natural speed, only adjusting that when circumstances dictate, and "letting go" of your attachment to forward progress when something stands in your way. Instead, you're driving at an artificially limited speed to try to regularize your driving experience. You're tricking yourself into feeling less frustrated by consciously eliminating frustration triggers from the driving experience; a zen approach would involve simply choosing to feel less frustrated by "realizing" that the frustration triggers really don't matter.
> Even though you'd assume leaving a huge gap in front is an invitation for other motorists to cut ahead, they rarely do - especially in congestion.
That's heavily dependent on time and place. I've lived in many different regions, and done a lot of driving in those areas. I've noticed that the tendency to fill in gaps is heavily dependent on local driving culture and the specific demographics on the road at a particular time of day.
> I absolutely swear by this driving method. It's easier on the car, easier on the heart, and even serves to create a bubble of calm around you in an otherwise turbulent flow of traffic.
That may, to some extent, be an illusion. Some people are infuriated by other drivers they perceive as holding them up -- which often includes people who are "wasting" lane space by letting a gap of thirty car lengths lie unused in front of them. Personally, I only get annoyed with such people when they try to keep other people from filling that gap, because as far as I'm concerned a steady gap (given a steady general traffic speed) creates irregularities in grouping through which ambient traffic can accelerate itself, but people who maintain a huge gap then rush to block out people who want to move into it are increasing the danger of driving and doing nothing to help improve the flow of traffic.