I measured up a lift up train seat for disabled passengers on a Melbourne train a few weeks ago. The seat is similar to the one below except that it lifts up to make room for wheel chairs/prams/bikes.
The seat is roughly two metres long and because I don't want the colors of the seats coming through I'm doing a thick stitch which takes some time.
It's a variation on a granny stitch but with a spike stitch in it that I found on the net.
I know that this is going to take a very very long time to do but I'm hoping to stick to it. I also hope to have a bit of an audience with me when I sew it to the train seat.