Hi there Raf,
Hope i can help you here. Firstly, you see a photo of a colored car that takes your eye and you like. However, what you must always bare in mind, is that photos never show the true color of a car - they lie, and so can only be used as a sort of reference to what you are chasing in reality.
So the only close way to assess a color for your liking is to go by a proper color name and color formula for that particular color. In your case,you will then need to see and examine the Acapulco Blue color in real life to determine if you like it or not. You basically have two choices here - you can have a small amount of this formulated color made up, and sprayed on a large test card for inspection, or find a vehicle that has been sprayed in Acapulco Blue, and see what you think of it.
Because you have expressed an interest in the Acapulco Blue color per say, i have given you a couple of references to what you're chasing. First is web page choc full of Acapulco Blue colored Mustangs or supposedly A Blue Mustangs. Notice the color variations are endless, and therefore can't be relied on for accuracy.
The second ref goes into paint codes for Acapulco Blue. You should be able to obtain a paint formula for the code, make some color up, and try it on a test card, and see if you like it.
Another way of approaching the selection of your favorite color choice, is to approach a paint company, and ask about viewing paint swatches that may be available to the public. Each color swatch should have a paint formula to go with it. Selecting a formulated color is important, as you may run out of color, and need to buy more. If formulated, you can be confident you'll be getting the exact same color as you first used.
References -
https://www.google.com/search?site=imghp&tbm=isch&source=hp&biw=1920&bih=943&q=acapulco+blue+mustang&oq=acapulco+blue+mustang&gs_l=img.12..0j0i5i30l2j0i8i30l6.2802.2802.0.9410.1.1.0.0.0.0.217.217.2-1
http://paintref.com/cgi-bin/colorcodedisplay.cgi?type=sample&ditzler=13357&syear=1969&smanuf=Ford&smodel=Mustang&sname=Acapulco%20Blue&name=1969_00097_01
Greg.