How are you going to detail the interior? If the car is clean outside, it must be clean inside.
A bottle of simple green mixed with water half and half. This will clean the dash and most of the stains out of your carpet. For the heavy duty stuff I use a steam cleaner. After you clean your dash follow up with some 303 protectant or goto Trak Auto and pick up a product called 3M Refresh rubber and vynal(sp?) protectant. This stuff is great! It leaves no shine. It gives your dash a clean matte, factory look and it comes in different scents.
-Antonio