They both look like they started with the same Pantone swatch, but Liquid Silver was given higher dynamic contrast.
To explain this a bit further, let’s look at a picture of actual Liquid Metal:
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Actual Liquid Metal has a very high dynamic contrast, it covers the full B&W spectrum from nearly pure black to nearly pure white. This contrast is also very sharp, in that it quickly transitions from dark to light, without a lot of grey in between.
Most silver cars don’t have much dynamic contrast (although even “regular” Silver tends to have more than other colors).
What makes Nimbus special is that it has higher than average dynamic contrast and that serves to highlight the surfacing of the car, which on Emira is a very good thing.
Porsche Liquid Metal to my eye looks like the same hue with the same degree of warmth, but with dynamic contrast ratcheted up even further, and transitioning from dark to light more sharply.
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Looking at these two images, the “average” grey is the same, but the Porsche travels further toward black and white, and doesn’t “live” at that average gray for very long. Under these specific lighting conditions, we see more of the surfacing live at the darker end of the spectrum giving the car the impression of being a darker color even though the average of the darks and lights is about equal on both cars. As lighting conditions change, the effect on the surfacing of the car would be more dramatic on the Porsche, almost like the color is in motion.
In short, to me they look like the same color utilizing the same effect to be special, but the Porsche turns that effect up to 11 (or, err, 62,000).
Edit: upon a little extra study Porsche Liquid Silver may also have a deeper gloss, giving it a bit more reflectivity which would heighten the “mirror” effect (further giving our eyes the impression of Liquid Metal) - but base grey is still the same.