It would be interesting to have opinion on what is the lumbar adjustment is supposed to do. I can't work it out. A knob is provided with obviously moves something inside the seat but it makes absolutely no difference to reducing the void in that area. I've noticed this on all cars, incidentally, not just the Ceed. (Though the Ceed would be better if the seat had some shape, with side support too, rather than being two flat slabs.)Try the full range of adjustments available, including lumbar (lower back) settings if available.