It's not quite a standard round up/down, and that might be where the confusion is. Technically, we're using a
ceiling function on all averages to create the graph. That allows us to plot full integers.
So in your example (as I look at the
Honda Insight page now), the graph says there are 3 at 49 and 8 at 50. So I think you're just seeing an odd spot in the data where there's a jump between integers. I know it's confusing to see so many 49.x's in the mix, but those are being counted as 50s.