"Tech Package with Autopilot" used to be a $4,250 option including a bunch of small features such as LED cornering lights, fog lights, and a rear trunk that opens remotely. I don't know whether all those differences were actually just access-controlled in software.

For the autopilot features, the difference was only software. Even before the Autopilot option was first available to order in October 2014, cars were being silently shipped with Autopilot-ready hardware for several months. For those cars, it's possible to call up Tesla with a credit card and enable the feature over the phone.