Previous to about 3 or 4 years ago, it was pretty rare to see “prototype” diecast cars being offered for sale.
These test run vehicles were actually fairly rare, unlike today, where we see these factory samples being sold on a regular basis (and mainly from 1 or 2 specific sellers, from Malaysia, where the Hot Wheels factory is).
And it’s not just a few diecast prototype cars either, it seems like ALL the factory test run pieces that were made are up for grabs.
Last years (2026 Hot Wheels model, but released in late 2025) Buick GNX had (at least) 50+ different test run diecasts produced.
[ see some of those samples here: purple GNX prototypes ]
And now, the 2027 HW Buick GNX (which is out now in late 2026), which is the light blue colored car, also has a multitude of test samples being offered up to collectors.
We previously showed you some of these 2027 Hot Wheels Buick GNX prototypes, and below are even more creations of this specific 1:64 scale diecast.
Some cars have plastic tires, some have rubber tires, and all have different rims on them.
Some have factory code numbers on the hood, some do not.
These particular versions have a yellow card attached, which is something new as of late (other test samples, and previous others from years past, did not have a card like these with them).
(we’re not sure, other than the yellow card, what makes these diecasts different from the other test samples that are currently being offered for sale without them)
[ the final released version of the 2027 GNX is here if you haven’t seen it before: Then and Now Buick GNX ]
Almost all of these prototypes sell for around $30 (which is about the opening bid for them), but a few of them reach $60 or more (mostly because of the cool wheel designs that are on them – which is the only difference between any of them).
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(there’s 3 pics of each test sample car)
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