I too suffer from sciatica. Mostly from years of abuse on my back and lack of exercise in recent years, but I attribute a lot of it to my previous car (Acura TL). The M's seats are a million times better and can easily be adjusted to support your needs. Previous posts have good info as far as seating position. Personally I cannot use a towel in the small of my back because it pushes me too far forward in the seat for my liking. For daily driving I relax the bolsters and raise my seat position up to ensure my legs are parallel with the floor as was mentioned earlier. Ensure your lumbar is fully engaged and play with the position of it to suite your needs. Hopefully you get some relief...I certainly share in your frustration!