The Upholstery Forum

In quilting we use what is called 1/4" tape. At the place where we want to mark a stitch line we use a ruler to measure where we want to sew and then position the 1/4" tape along the ruler to mark our stitch line- then we sew right along the 1/4" tape. To keep the ruler from moving tape the ruler to the table once it is positioned, before laying the 1/4" tape for the stitching line. There is no mark to erase. When the stitching done just pull off the tape.
Is this a method that would work for marking stitch lines on vinyl car seats?

I use a sewing guide as shown, or I have made another that mounts to the machine. Hope this is what you are talking about. I generally use 1/2" sew allowance.

I have never seen anyone do it that way. I assume that it would work. However I think that would be quite a bit more time consuming than measuring and marking with one of the many options available. White upholstery pencils are my favorite for vinyl.
https://www.perfectfit.com/product/Marking-Pencils