Color code conversion

I originally posted this 3 days ago under 'Care & Maintenance (Styling & Car Care)' but can't get any advice. It seems there's a lot more visitors here so allow me to try one more time:

How can I convert certain color code from manufacturer coding to let's say HEX or HTML or RGB? It doesn't really matter which one because I only want to see that color on the computer screen. I want to know if it's possible so I can compare different colors from different manufacturers. For instance I want to see the difference between Skoda's Topaz Brown (LF8Z) and Kia's Matrix Brown (J5N). I know it's not the same as comparing in real world but I want to see the difference in digital form.