POLICE are warning motorists in and around Newton Abbot to secure their vehicles after a spate of arson attacks on stolen cars used to commit burglaries.The cars have been 'torched' by thieving fire-raisers reckoned to be behind a string of local break-ins during the last three weeks.Insp David Hammond, Newton Abbot police commander, wants motorists and owners of business premises with commercial vehicles to do all they can to make auto-thefts difficult for the 'opportunists' at large.