Here's what I've gathered from looking at videos, photos, and general dimensions. I've used photoshop to corrected aspect, warped images, and come up with the drawing below. Everything in Green I am very confident. Red, I am unsure about. Yellow means it can be calculated. I believe both smaller left side "blocks" (showing 1750mm) are the same length.
They Ali one I have seen, does not have the correction dimensions. It measures 700mm wide, but we know from all advertising that it's 800mm. It could be that the dimesions they used could work just fine.
I believe that dimension "A" and "B" are the most critical. We know "A" (length from white box to wheel center) from VW YouTube videos and ODIS screenshots. "B" on the other hand is not really well known. The one an Ali measures 1760mm, but I can't trust it.
Does anyone have access to authentic calibration mat that can measure "B" ? Or any other dimensions?
First drawing is the hand sketch I found. The overall length doesn't add up exactly, but we know it's 8000m. A lot of my assumptions from my draft drawing earlier were correct.
The second drawing is what I believe to be the correct dimensions. I'm not in a position to test this (yet), I want to modify my Ali Express one to match these dimensions (I need to wait until summer when the weather improves!). Also, from my earlier searching, it would appear the area calibration system only seeks the white areas of the mat, so you could get away with putting down white tape with the correction dimensions on a black driveway.