There's a lot of silly debate about all of this, probably stemming from the nuisance of paparazzi and their invasion of privacy of public figures but it seems that you may have the right to stop people photographing your private property.
Of course the driver mentioned by Mr T was just an idiot but it seems to me to all be a stupid legal mess.
Does a private car on a public road carry such implications? Who knows.
http://www.sirimo.co.uk/2009/05/14/u...ers-rights-v2/
Sometimes I have been asked by drivers why I am photographing vehicles - usually a polite explanation is enough to assuage any fears. People may just be worried that I'm looking to find fault and report then for something or other so if they are not happy of course I will err on the side of caution and resist.