It is a gorgeous color on these cars even though it isn't a VW color. And you are wise not to try the fender beading on your first Beetle: This was my first attempt but my fifth or sixth Tamiya Beetle, so I knew what I was getting into. I did it with very careful and very tedious Tamiya masking tape application, and it ain't easy! I'm sure you'll build this kit again because it is addicting if you like VWs. My only real complaint is that the taillights are molded in clear plastic and have to be masked to be painted body color, and that ain't easy either. My windows are done with Bare Metal Foil. Here's a helpful tip: put a piece of masking tape over most of the window surface before applying the BMF and you won't get adhesive residue on the "glass" that has to be removed. And to further create a realistic look, you can run a black Sharpie around the window frame on the body to simulate weather stripping, and you can run a fine-point Sharpie around the window frame on the glass parts to both burnish down the foil and to simulate the gasket. Good luck with your project and make sure you tell your daughter that I've sent my compliments on her excellent taste in cars and colors.
You've proved conclusively that those Heller kits of classic French subjects can, in the right hands, be built into very fine models. They do repay a modeler's patience. I love the colors you've used. Tres bien fait, mon ami.
I use Tamiya TS paints decanted from the spray can for my airbrush and mix them to suit my taste. That's is what I would do in this instance if I were building this Audi. As I said, I see lots of red in that particular picture of that particular orange. I'd start with the TS-12 or maybe TS-56 (Brilliant Orange) and add TS-49 (Bright Red) until I got a match.
Scale Finishes also offers an Audi color called "Samoa Orange" that is probably suitable. I would just use Tamiya black and orange. The photographs you linked to don't capture the colors well. The orange looks like it has a lot of red in it.
Every update you post makes me happy. The engine bay is looking very good indeed. There's so much detail at that scale and all the little wires and tubes and hoses add to the overall effect. Keep it up.