Works wonders. Once used it on an ex-gamekeepers Range Rover before I sold it.
Got rid of the wet dog, mouldy grain and dead furry animal smells very well. I suppose it is possible the smell came back when the Fabreze wore off but I'd got rid by then
Place a bowl of white vinegar and water 50/50 split in car overnight, you might have to do this two or three times depending on how much of a heavy smoker your ex was.
Do you have a dyson or similar? Sprinkle baking soda into ashtray, carpet and seats. Leave for 24 hours before vacuuming. You need a really really powerful vacuum for this or you will never get it all up again.
If you don't want to try the baking soda, try a product called Neutrodol. It comes as a spray and in a little pot like an air freshener which you can leave under one of the seats. It is a brilliant product but not many places stock it anymore. PM me if you can't find it.