I got my new Bolt EV LT yesterday after a lot of testing of the front seats. While I found that raising the seat height helps shift weight forward and somewhat off the ridges towards the back, I couldn't find an adjustment point that was totally satisfying.
This youtube video with a fix may be posted somewhere on ChevyBolt.org, but just in case... here you go. These directions are great!
What's not covered in the video is how much and what shaped of foam to use. I have photos of what we just did.
We purchased a roll of high density cushion foam at Joann Fabrics. It was 1 inch thick. 24x36 inch is plenty, though our roll was six feet, in case we experimented too much :-)
As noted in the video, heated seats have a cable to avoid, so we came up with the following pattern. It was easy to slide in left and right halves, plus a little extra across the back. This provides a wonderful boost to seat cushiness above the ridges.
This worked with a cloth seat for us. The original youtuber, robertlmathews, upgraded leather seats, so I assume that can work either way.