Will your break lights (or some other warning light) come on when you lift your foot off the accelerator, even if you're not depressing the break? Seems like there should be some sort of warning to the cars behind you that you are slowing. This seems to be especially true in eco mode which, according to what I've read, has increased regenerative braking. So even though you're not using your brakes, you are deaccelerating quicker than an ICE vehicle would normally.