The interior of my '59 544 was completely re-upholstered by the previous owner but he should have rebuilt the front seats first. They offer little support generally, collapse at the sides when I sit down, and really are atrocious. Does anyone know of rebuild kit? Failing that, a useful replacement seat? I'd like to maintain originality but I'm much more concerned about the car being comfortable enough to drive. Any suggestions welcome.

Not that seats from a B18 544 would be that much newer (post '62 or thereabouts), then your's but they are more comfortable than the B16 seats. If you had a source of used, "later" passenger seats and backs you could swap out for your earlier ones, that might be a better "original" ride. I believe that the seats and backs were interchangeable from side to side, and passenger seats are always less beat.

I found the earlier seats, being convex and slippery to be un comfortable. The backs on the later ones seemed better built and upholstered than the earlier ones.

The PV seats were certainly made for skinny post war Swedes and didn't change much over the years. It's also pretty snug in there. They can be rebuilt to be a bit more supportive if all the insides have collapsed, there's a lot of old timer stuffing in there. VW Beetle seats of that era and a bit later are very similar in style and shape. They can be swapped in or the foams and stuffings can probably be adapted to the PV seats. Lots of custom Beetle upholstery shops out there.

I have the same issue on my '58 444. When you sit in it, both front seat occupants lean towards the doors. The PO just had the seats re-upholstered but not rebuilt as well.

I took the seat outand wired the spring frame thingy to the actual bars of the seat frame. This gave me some extra support, but I would think there are a lot of failed springs and old foam in there.

If you can, I'd find a place that can rebuild the seats for you. If you want, you can find new seat skins from the various vintage volvo places, but it's probably more money than having a shop re-upholster them. At least it will look original.

I've seen plenty of PVs with modern seats or seats from different cars. They look good, but it's not for me...not in this car.