Ever had a car stolen in or around London? Worried about the risk of buying a ripped-off or cloned used car? Want to know how the country's top Police go about tracking and catching car criminals? Then log on to www.webchats.tv this Wednesday, when you'll be able to put your questions to detective chief inspector Stuart Dark, who's head of the Metropolitan Police Stolen Vehicle Squad, and probably the top car theft cop in the country.DCI Dark will be online at 3.00pm on March 28, and will be advising drivers on how to check the veracity of their cars, the validity of its documents, and how to spot a genuine bargain from a nightmare-on-four-wheels. He'll be joined by DVLA and Department for Transport spokesperson John Moore.The Police estimates that between 30,000 and 40,000 cars are rung or cloned each year, while 33,000 number plates were stolen in 2005. Young drivers are the least likely to ask to see registration certificates when buying a car, a DVLA survey found. Some 14 per cent of 17-24-year-olds wouldn’t bother to check for a V5 certificate, it reported, compared to just 4 per cent of 25-34-year-olds.