Though Medium Yellow Gold looks no different than what was used in the film, Halicki claimed (in a personal interview with forum member Kit Sullivan, back in '74) that the cars were painted a generic school bus yellow for the film.
Given that the restored prints of the film are hardly color timed (these days, it's called color grading) at all, it's hard to say what was the true color of the car - and that's not even factoring in the difference between monitor settings and whether they're showing true color. None of this is truly accurate without testing any one monitor with color bars and a vectorscope.
Monitor differences aside, this is a screenshot from the 2005 DVD release (ASIN B000A3XYHI), without color grading. The Mustang looks to be a mustard yellow:
This is more or less what 35mm film looks like when you don't try to adjust the color timing chemically. Think of the hazy look of color 35mm still pictures from the 1970's and older. That's before Eckerds and Walgreens quick-processing got on the bandwagon of color timing your pictures for you.
If I had been color grading the film, I would have graded that shot as follows - not based on the Mustang so much as the color of the park and the Plymouth Barracuda(?) behind it. Again, this is my
opinion - grading is not set in stone (as the remake of Gone in 60 Seconds sure proved - talk about crushing your black levels), and I still think the red saturation is too high (note the tint on the trees):
Then we have this 35mm scanned behind-the-scenes still from the film, which looks like bright yellow - and may have been digitally graded by Mustang Monthly:
Yet, the same car, photographed a few years ago, looks nearly identical to the shot I color graded.
Not much consistency. Do I believe the "school bus yellow" color is close to Medium Yellow Gold? Yes - close enough to me, which is one of the reasons I wound up buying (a bad mistake!) a completely trashed Medium Yellow Gold '72 to do the same thing with. Chances are you'll get a lot farther than I in a shorter amount of time, but I've only got one car ahead of this one
Speaking of which, notice that the tinkering that I did with the saturation in that shot makes the Medium Yellow Gold a lot richer than it is. This is the same car on another day, without that HDR-esque look that the saturation adjustment gives. Looks like that "school bus yellow" of Halicki's to me. Get a load of the handicapped sign on the left - that was a driver's floorpan "repair."
Agian, for easy visual reference:
FYI, I posted a complete analysis of these cars and the scenes in the film (close to 100 screenshots) here:
http://www.7173mustangs.com/thread-gone-in-60-seconds-1974-eleanor-observations-was-halicki-really-a-car-thief-etc
It's a must-read if you're doing a replica.
-Kurt