I believe some model years actually didn't have a low fuel warning light.My 98 Mystique has one, but I remember reading that some of the earlier models didn't. As far as an audible warning , I don't think any Contiques were equiped with that. Somebody correct me if I'm wrong....it happens sometimes.
Your best bet is probably just to keep it above 1/4 of a tank. That's better for your fuel system anyways, especially in cold weather.