This one just worked for me in Chile for a 32 day rental:
sixt ... /apartmentservice/ (cannot post links) - google it with apartement sixt (it's on thecoorporate partner page)

15% off the rental rate. Is there a problem if you are not member? The booking shows simply 15% off in the rate and appears under my account booked. Problem in case of accident or when pickung up? Would be nice if someone can add in the title what happens if you use a code without being eligigle.