Icarus,
"The velocity of light 'in a vacuum' is the same in all frames of reference (for al observers) moving uniformly, relative to each other,
I am not certain that the post mentioned that the car was being driven in a vacuum?"
Just a quick question; If the speed of light is considered as constant then why does it matter if this is in a vacume or not? surely this would therefore make no difference to c?
AA