Best way to improve image?

[Dave-ROR]

So I went from Fantastic in image to Abysmal in about 2 months. Granted I had some old car models selling still (couldn't produce enough of them so I didn't stop making them yet) and I wasn't racing, but I thought that was quite the extreme drop (and sales went from 100% sold every month to about 10%). I redesigned everything, and sales went back up for a few months but the image ranking never changed. Started racing, and kept redesigning models often (every year or so) but the only way I could keep sales is by staggering those and I never returned to the level before the image dropped.

Now with 1.15.4 it doesn't matter for my old game, but I wanted to see how the rest of you improve image once it drops for whatever reason.

Thanks!