You still do good work! Let me see if I can't dummy up some data and produce the chart I can attach here from the one in my head. My general thinking is this, for any given date or week of reservations, how many reservations were made that week over time a growing number of those reservations (orders after 6/28?) will be filled. So for the week of 3/27/16-4/2/16 6000 cars were reserved, as of today 3000 have had assigned vins and 1500 have been delivered. The farthest back area would be reservations, middle area would be VINs, and foreground would be delivered. So you'd need an intermediate table where each row is week number or week range, column 1 is reservations, column 2 is VINs received, column 3 is # delivered.
While neither #vins nor #delivered will never exceed #reserved (remember this is #vins and #delivered against #reserved. So each column would be #count(where date contained in week) for reserved, vin received, delivered. Such that, on a daily basis, everyone can look at the week their reservation was made and see how many, reservations from that week, have had vins assigned or been delivered. As neither can exceed reservations generally delivered will be <= reservations as well as <= vins. The resulting chart would visually be a wave over time of %completion of backlog. Lets say delivered color is green, the green mass would move from left of chart to right of chart. I think visually it would be a very simple yet dense information chart. Make sense?