GPS is required for SpeeedLimit. If GPS isn't inbuilt, you should use an external GPS receiver.
You need for comprehensive warnings: the software SpeedLimit 1.2.5 (for free) and the latest database for SpeedLimit 1.2.5 (fee required)
the software SpeedLimit 1.2.5 (for free)
and
the latest database for SpeedLimit 1.2.5 (fee required)