DVLA will give anyone your details,send them 3 or 4 quid and you will get the owners details by return.
http://www.direct.gov.uk/en/Motoring/Ow ... DG_4022067
You have to have a reason such as being in an accident, and give the police officer's details you are dealing with. They don't just pass them out, they corroborate with the officer first. Not saying it's foolproof, but it's very difficult to get info out of them. I'm in the cops and it's not easy, like blood out of a stone sometimes. In reality, little scrotes would just bin the keys and joy ride the car for a while. I doubt they will go to the effort of blagging the DVLA and pretending they'd been in an accident, and having an inside source in the police to confirm their story - all to steal a 350Z. Maybe if it was a Bugatti Veyron worth more than £15k it'd be worth it.