I just purchased a 2011 LS460L and am super impressed with the car and its comfort. Except for the driver seat.

I thought I was going crazy because I couldn't believe the seat was that uncomfortable. Then I googled....

And low and behold there were all kinds of posts about the same problem.

So, I bought a used passenger seat bottom. Typically, the passenger seat on most cars is similar in shape except that they have no wear. Now, I bought this before I discovered that new driver's seat foam for the LS460 was cheap ($190). I would recommend a new bottom to future searchers.

But, after disassembling the driver seat the problem becomes evident. The foam is split where it sits on the seat pan AND there is a weird "ridge" internally in the foam seat bottom.

This "ridge" seems to be a hardened section of the foam to protect against wear on the edge of the seat pan. On the pic with my thumb squeezing it, you can feel a distinct ridge in the foam. I'm betting that some (sensitive) people feel this ridge when the car is new and then others are feeling the seat pan edge when the foam is worn through.

So I shaped the used passenger seat bottom to fit on the driver's side, then added 1" memory foam to the top of the bottom cushion (where you see the green stock foam) as well as some very thin foam headliner material to ease the transition between new and old foam.

If you are someone that would take it to a professional then just tell them to add some foam on top of the seat bottom and they are very likely to get it right.