'06 which has 4 inch fine line split in driver's side seat located not on seat itself but on the side facing driver door. Was going to take some black duct tape and use it but maybe it won't hold as it will compress everytime the seat is used. Any ideas or experience?

 

The seat is dry, and brittle. Need moisture from a good conditioner.
Take it to a car upholstery shop, and See If They Have a solution.

 

Easy Repair from a pro ..
Can the tape