[RedDevil]

And Neutral in the Insight is actually Neutral, with the engine ticking over at Idle where it would DFCO if it were left in D.
So it will actually use more fuel in Neutral then when carefully matched with the throttle to defeat regen. Or given a little more throttle to prolong the glide under mild electric assistance, or deliberately left unthrottled to get regen while mildly braking to prevent overshooting the destination. There is some flexibility in that range to play with.

I like the regen though because it will use the power to accelerate again, and you don't want it to regen while maintaining speed after acceleration to replenish the battery while you could have gotten that charge from deceleration.

Also, the Insight is a keen roller. I generally need to decelerate harder than just coasting when leaving the highway etc. The deceleration under mild regen is about the same as the other cars do when they just lift the throttle, or maybe just a fraction more.
The point is, I can roll along with the other traffic leaving the highway without having to touch the brake pedal, if they don't brake too.
I dislike having to light the brake lights when just losing speed at the same rate as the other cars when they don't brake. So I am happy with the mild regen.

IIRC the Tesla model S can be driven with just the accelerator pedal under normal conditions as it will regenerate strongly when you lift off completely. I wonder if that makes the brake lights burn?