Neutral Lower Back
Nowadays, most car seats are what are called "bucket" seats where the seat slopes downward toward the backrest. Unfortunately for our lower backs, the higher front edge of the seat pushes our thighs upward while the slope of the seat encourages the pelvis to tilt backwards. This backward (or posterior) tilt of the pelvis flexes the lower back. So, if we're sitting with a tucked pelvis and a rounded lower back habitually, you end up at risk for:
pelvic floor issues
lower back strain
collapsing forward with the rest of the spine
chronically tight and unresponsive hamstrings and glutes in your walking and standing
Some people give the illusion of straightening their backs by lifting their ribcage/chest to compensate for the lower back flexion, but this tends to compress parts of the lower back even more.
So, we need to start with bringing the pelvis back to neutral by first creating a sitting environment that is more conducive toward tilting the pelvis more forward than back.
A neutral pelvis/lower back is when there is a slight sway in the lower back at the level of the sacrum and the front of the pelvis is vertical from the top, side pelvic bones (ASIS) to the pubic symphysis.
An easy way to adjust the seat is to fill in the "bucket" or slope of the seat with a towel or half foam roller:
place the towel or roller at the back of the seat and sit on top of it. This allows gravity to work in the opposite direction as a bucket seat and will encourage your pelvis to tilt forward.
Another option is to place the towel or roller as a support on the lower back. But be careful! Don't place it higher than the pelvis. This will encourage rib thrusting and does not actually help the hips and pelvis themselves find their neutral position.
