Deep Cleaning

Almost every square inch of the interior of my car is disgusting. Probably 46 years of dirt. I've bought some Chemical Bother's upholstery cleaner and used it at the lowest dilution. Scrubbing and scrubbing with a stiff bristled brush on the inside of the driver's door, the driver's seat (MBTex I think) and the padded "horseshoe" section at the back and I am disappointed. I don't see any real improvement. My fingers have pruned though!

I see that in the past Aerospace 303 is recommended for protecting and also Lexol, but what about deep cleaning? Is there something out there that can do wonders for my tired old interior? 🧐 Should I get one of those brush attachments for my drill?

Thanks, Andy