[kach22i]

First pass, sketched it up.

Purpose of tail-fins:

1. Lane Presence - to occupy full lane front to back, avoids crowding.

2. Safety - LED strips in cross pattern or round dots going to get noticed

3. Stabilization - I've never seen a dart without tailfins - just say'n

4. Strength - something more to crush than your spine, crumple zone.

I suppose with some imaginative thought a few more reasons will pop up, like easier to right the vehicle should it end up on it's side.

EDIT:

Small fish with spines say "stay away" even from a distance, which helps make up for their lack of largeness or size.

Bright colors that say "I'm poisonous" do much the same.

In my opinion, you want something that gets a little attention, and says stay away.

There is a danger on the road of creating a visual so mesmerizing that the driver of a car drives towards what they are starring at - a bad thing. This is why early experiments/practices of motorcycle riders wearing orange helmets and or road repair crew type vests ended so badly.