Interesting suggestions, Although in my opinion it's been way overthought..I believe its as simple as subtle shading and VERY subtle highlighting over a Semi Gloss Black base.
For this, to match the original I would use Alclad II Prismatic Scarebus. Depending on the light it can look Green or blue. Just like the original paint job.
Here is a model with the Scarebus paintjob-
Seeing as your painting a Studio Scale Batmobile, the metal flakes should look well in scale.
Now, here are a few references to illustrate my point.
Real 89' -
Screencap from Batman -
You can see how subtle it is in the film but, it's there. I'd recommend VERY lightly shading it over the base, don't make it obvious. There are many more photo's on Chickslovethecar.com that show that multi-colour shading.
I'd recommend going over and saving some pics to use as reference to get the locations on the paint right. Be sure not to mix up replica pics with screen used ones.
I hope this works, if you need any help let me know.
