To echo Mike, I always request rollbacks/flatbeds for my classic Cadillacs and especially a big CC. It's also my understanding from talking to a number of tow truck drivers that towing any RWD car by the front wheels with the rear wheels on the road can cause damage to the differential. Don't know if anyone has heard the same??
If the car is an automatic, the drive shaft needs to be disconnected because when the rear diff turns it causes the pump in the transmission to turn , which will burnit out. If its a standard transmission, it needs to be put into neutral. But I would'nt want to go very far like this. Its much better to ROLLBACK it. Just my shadetree opinion.