Oh wow is that teal, no

probably royal blue...
https://www.nytimes.com/2014/04/19/automobiles/a-mustang-option-matching-nail-polish.html

What if for your nephew's birthday, you just get some cool nail art...
http://m.nailartgallery.nailsmag.com/photo/263730/my-cars

or
https://www.coloribus.com/adsarchive/tv-commercials/kia-picanto-picanto-nail-art-animation-17814455/

and
https://www.zazzle.com/vintage_amish_nails_minx_nail_art-256364210418859170

anyway
https://www.vampyvarnish.com/2014/07/opi-ford-mustang-collection-swatches-review/