In 72 the color code would be A4. It was also avaiable in 71. In certain light it does look blue. The 73 gray color is A5 and is quite a bit darker...and doesn't look blue.

The color does look like A5 in your picture but that was a 73 only color. The side stripes in that picture aren't the 72 style. That's the 73-74 style stripe. Could the car have been repainted A5 instead? Check out this link. It is a color chart made by one of the members of this site. The color names are different for Dodge but the accual colors are the same.

http://www.aarta.com/challenger_colors/challenger_colors.html

I really like the V21 option with the A4 color. There is an A4 72 Cuda that shows up at the Mopars on the Mississippi show almost every year. It doesn't have the V21 option though.