Is it impossible for third parties/ service providers to pass on my BMW CarData data without my knowledge?
No. BMW has no influence on what third parties do with the telematics data. Should BMW discover that the telematics data is being used for a purpose other than that authorised by you, this would contradict the BMW CarData GTCs for third parties/ service providers. In this case, BMW reserves the right to block BMW CarData Services for the third party/ service provider.