The Active E is smooth, as in groovy smoothy. It has very little vibrations because there is no gas engine whirling around under the hood. The only noticeable vibration is from the road, which is slight most of the time. So a smooth ride in the E is a sign of all systems go. But when a vibration creeps in, that's a sign of something not so go.
Last week I pickup up a hitchhiker in my front left tire--a rather large screw.
In hindsight, I knew exactly when I picked up the screw because I felt a noticeable vibration coming from the front left part of the car. I checked the tire sensors and nothing was amiss so I brushed it off as excess vibration from the road--it was a rough bit of asphalt. When I stopped the car I couldn't find anything (the screw was on the inside part of the tire--very hard to see). So I did what you shouldn't do with a screwball tire, I drove home on the freeway.
The screw held tight, and so did the vibration, so I checked again. Sure enough I found the unwanted passenger lodged deeply in the tire. The tire didn't lose pressure until the next morning--so apparently there was a slow leak. A quick trip to the tire store, the tire was patched and put back in service (whew--no new tire needed).
The interesting point in all of this is that driving a car that is groovy smoothy allows you to notice almost immediately when something is amiss. In a gas-powered car I would not have felt the difference in vibration coming from the tire, most likely, because the car has so many of its own vibrations. My only problem is that I ignored the vibration.
Now if only I can pay attention to my feelings....