If someone wants to steal a car they will if they are determined and resourceful enough.
However the 5 series in general is one of the most secure cars on the market.
In the UK What Car does an annual survey of the most secure cars which they have 'attacked' by professional thieves.The M5 passed the test with flying colours lasting over 5 minutes before the thieves gave up,however as the other guy said if they have a flatbed etc then you are in trouble.If you are that concerned best thing is to fit a tracking device.
However the 5 series in general is one of the most secure cars on the market.
In the UK What Car does an annual survey of the most secure cars which they have 'attacked' by professional thieves.The M5 passed the test with flying colours lasting over 5 minutes before the thieves gave up,however as the other guy said if they have a flatbed etc then you are in trouble.If you are that concerned best thing is to fit a tracking device.