I have disabled the lumbar and it helped a little. I found the biggest contributor to my back pain (it hurt my back since day 1) was the seat position and angle. I preferred to be lower in the car, however, when you lower the seat, the rear of the seat bottom goes down at a progressively increasing rate, relative to the front of the seat bottom, so you end up being at a very steep angle. I ended up raising my seat up to where my eyes are basically level with the rear view mirror and I noticed my back did not hurt as much. I went back to the lowered position for a 15 minute drive home one day and it hurt for the next 10 hours. I have since opened the seat bottom and added foam to try and both raise the seat bottom relative to the seat back, since that's where I thought was a factor too, and I've put about 3/8" of washers under the two rear seat mounts to try and raise it up so the angle isn't as bad. This seemed to be fine for months, but just starting last week my back has started to bother me a little more and I'm not sure why. Up until adding the foam and washers I was undecided about keeping the car, but then it wasn't bad, although I feel like I'm driving a 4x4 sitting so high, and decided I will keep it, but now with this latest re-occurrence I'm kind of unsure again. Maybe I'm more sure than I think because I've finally been looking at mods which I held off on before.I noticed it at some point on a long (round the country trip) taken not too long after I bought it. It killed my back, still does -- although I basically got to where I was ignoring it because I'm commuting in it (which just means I forget why my back hurts lol). I had them warranty repair the lumbar a couple years ago and it basically came back "less bad" but still sucking ... or so I thought, after moving the seat from it's one "meh" position now I feel it again. Doesn't get better over time (has 22K on it now). The passenger seat is fine so might try disconnecting the lumbar, otherwise it's getting traded very soon for something else.
TLDR the seats are too soft, the seat angle gets too step down low, and the lumbar support is way too pronounced.