In fact, if the car doesn't recognise your bum, you won't be able to drive it at all - let alone steal it. New anti-theft technology developed in Japan relies on biometric recognition of your derriere.
The driver's seat squab is embedded with sensors that measure pressure and distribution, creating a 3D plot of your rear end. If the driver's seat doesn't recognise that part of your anatomy, the car won't start.
The system has been developed by Engineers from the Advanced Institute of Industrial Technology in Tokyo.
Reports say it was able to recognise and give the 'permission to drive' nod 98 per cent of the time to six different drivers' arses, but didn't say if the seat could tell them from elbows.