BMW unveils car sprayed with Vantablack
That seems really irresponsible, the car would be very hard to see if you approach it from the rear at night, especially if the driver installs covers over the brake lights to make them darker.  A few years ago where I live in the USA there was a news story being run about a controversial decision to not charge a driver who hit and killed somebody at night because the person they hit was black, wearing all black clothes, and walking in the street.  I don't imagine a car painted with a material known to make the car close to invisible against a dark back drop would do any better in court if it was rear-ended.