OK a bit more of an update....
Rear seats etc:-
I finished these off a few weeks ago. Not tackled the backrests yet but probably will at some stage. Sewing is harder than I thought - when you've got to sew perfectly straight parallel lines. The original ones were done with a twin-needle machine. I had to do them by eye. After a few goes I got to the stage where I was happy with the straightness but the stitch length just wasn't right. I've put them in my car but I'm going to get them re-stitched by an upholstered in the new few weeks. He's done a test run which is a bit straighter than mine but the stitch length is spot on.
As an example this is the bit behind the rear seats (not happy with this but was justifying on the basis that you never see it)
And here is one of the rear seat squabs in progress - couple of important tips - masking tape is way easier to follow than tailors chalk; and when following a line, follow it against the foot of machine - not against the needle - the constant movement confuses your eye and you'll go wobbly
And the seat squab finished - by now I'm getting better at the straightness.
When you look into the car they really look fine. But if you look closer and you're looking at the stitchin it's not right. So that's why I'm getting them re-done professionally (but he hasn't got a twin-needle machine either)
Compared to sewing, upholstery on the other hand is a piece of p155 (By upholstery I just mean the sort that goes into our cars - not making sofas). Bit of foam, cutting, gluing and stapling.