Scientists created a paint so black it makes cars look like silhouettes

[Endymio]

More efficient thermal absorption/emission is the only thing I can think of.
Radiators, heatsinks, etc...

It's highly useful for reducing noise in telescope optics, thermal sensors and the like.

If their lights are off (say they are parked on the street). It would be almost impossible to see

A fair point. If I purchase one, I'll be sure to keep it garaged.

 

[netman]

"A new carbon nanotube composite absorbs 99.9% of visible light"

It also absorbs 99.9% of HEAT...!

It better have a strong air conditioner like the American cars... Since the designers are European I very much doubt that... So if you live in a hot climate think twice before buying this car...!

 

[Gars]

Already done: a paint so white it literally can cool whatever it's painted upon:

The whitest paint is here – and it’s the coolest. Literally.

In an effort to curb global warming, Purdue University engineers have created the whitest paint yet. Coating buildings with this paint may one day cool them off enough to reduce the need for air conditioning, the researchers say.

www.purdue.edu

I meant so white that it could be seen in an unlit space and no poluting lights

 

[ActualViking]

The Vantablack color part is not new. What’s new is that the researchers claim they’ve made a coating that can be applied using conventional automotive paint processes while maintaining similar ultra-black properties. The engineering challenge has shifted from making it darker to making it practical. That's what today's story is about.

Practical?
Making a car hard to see isn't practical, that is dangerous.

 

[BadThad]

Let's see how it survives living in Arizona for a few years. I see no mention of it's thermal properties. With high photon absorption as claimed, that radiates as thermal energy, the surface has got to be absolutely scorching hot in the sun.