do what i did. pull out the old carpet. clean the area really well, and go to a RHINO LININGS place. they have a spray on urethane bed liner for pick up truck beds.
i got them to spray the whole damn inside of the car from the windows down and they charge me only as much as a ford ranger pickup bed.
it was like $175. they use tape to mask off things like gas petal, e-brake and such.
spray everything down. man the stuff works good.,