Hmmm.
I've only had SE spec cars because the Msport seat, side bolsters stick in my ribs...
I've never had the lumber support as an option because the seats seemed to provide adequate support.
But with my latest 325d, I specc'ed leather seats.
I never gave a thought that they might be different.
They don't seem to provide the same support as non leather version and I had a painful back for a while initially.
But since my recent bout of sciatica
- caused by nothing to do with the car - it's paled into insignificance.
At least it's getting better now
