We've been down THIS road before, I THINK I can get this right from memory.
In a BASE model, you get:

No silver trim around the windshield, no silver door handles
No silver side stakes
No fog lights
Black, not silver air intake/engine cover
Cheapy sound system with less power and no speakers (subwoofers) behind the seats and no option for Navigation in the head unit
Manual Transmission only
Black exterior, monotone black interior
No TPMS
No Garage/Gate door opener
No "Crossfire" chrome trim panels in the door frame openings

I THINK that's it. Both Coupes and Roadsters were built in "base" model, but not SRTs.

The "Special Edition" roadsters were a Base model with:
SRT rims
Red exterior paint
Silver Side Stakes and Door Handles - but black around the windshield like a base model