How fast does your car have to be going deploy the side airbag on a 2001 Ford Taurus special edition luxury?

A 2001 Ford Taurus, or any car for that matter, doesn't deploy side airbags based on speed. Side airbags are deployed by sensors that detect a side impact of sufficient force. The speed at which a collision is hard enough to trigger them is variable and depends entirely on the angle and severity of the impact, not just the speed of your car. A slow-speed, but very forceful, side collision could trigger them, while a high-speed glancing blow might not.