These cars are believed to have been used for 1968 Hot Wheels Commericals.
A large group of them came from a Mattel Photographer who primarly shot TV Commercials, also a Mattel liaison engineer.
They are not Salesmen samples, there are far too few.
Mattel had a sophisticated advertising department, with incredible success in using TV to help sell its toys, and of course newspaper and other print media were a vital part of the Hot Wheels success. With the introduction of these new toy cars coming to the stores in May of 1968, Mattel knew it had to show them in the best light. With that in mind, the plant manager in Hong Kong was instructed to make the first batch of cars shine like ‘Christmas Ornaments.’
And so they did, shining like no other toy car at the time; barrel plated and then painted, and their undersides looked like bright chrome. The plant manager told a fellow employee it took a long time to make these cars, and with orders of huge volumes of cars from companies like Kmart, mass production needed to be fast. So just that one special batch was made, no more. That one batch were the ‘Over Chrome Cars’ and are considered to be the "jewels" of the hobby. They are exceedingly rare…. Around 30 are known to exist.
Of this casting/color, there are 2 that are "known", one stapled to an early 10 car card with missing button, one loose.
They are not Early Prototypes, as the castings are all from later in the production runs.
They do not appear to be Catalog Cars as so far not one has been identified as being seen in a Catalog.