Up to 40,000 more trucks and trailers may need mandatory annual roadworthiness tests in Britain if a proposal from the Department for Transport (DfT) gets the go-ahead.  A current consultation document proposes the DfT aiming to end the exemptions that apply to many truck-based vehicles such as breakdown trucks, tower-wagons and mobile cranes.  Also in the firing line for the first time are abnormal-load trucks and trailers run solely under the Road Vehicles (Authorisation of Special Types) Order 2003.  Deiver and Vehicle Licensing Agency data indicates around 14,500 breakdown vehicles alone registered on UK roads.