Castrol Demo "Oil Cam" - personalised billboards based on number plate recognition

So their camera uses license plate recognition; passes that to DVLA; gets the make and model; then tells you this & to go buy better engine oil for your make of car on a digital billboard directly ahead. Kinda cool, kinda freaky... as long as they don't follow it up with a direct mail piece then I'm OK with the use of that data (just). OK. No. I'm not happy with them using me driving my car as data capture. Why don't they just buy the data normally and mailshoot the entire driving community and personalise the mailout? this billboard would just freak me. And it probably will - it's just down the road.