Check your boot and spare wheel well, water leaks in badly round the tail lights. My thing was stinking, had to remove all the boot carpets, linings etc to allow them to dry out. Clear silicone sealant stopped the leak at the tail lights.
It did smell like some sweaty old fat gits ar5e crack too :chuckle:
My R34 has a very distinctive smell, it's NOT bad, just different...I like it. I just open the doos and I get a whiff...still have no Idea what it is, but the car can sit for days with the windows open and it's still there!