I had an elderly cancer patient cat that couldn't hold it anymore (the vet was not close, long story) and she peed on my passenger seat. Not a little dribble, not a spray, but an entire bladder. I didn't even realize it at the time, but I went back to the car for something and saw the whole seat was wet. I drove immediately to the pet store and bought some Nature's Miracle and soaked the effected part of the seat. It took about a week to fully dry, and then I could smell a faint hint of cat pee when I first got into a hot car, and there was a line where the Nature's Miracle had been drawn up into the seat back. So the second time I wetted down the entire seat cover and that did the trick, haven't caught even a whiff of it since. And I have a very sensitive nose.
My only concern is that my side impact airbags are located inside the seats and I'm guessing that alcohol and enzyme cleaners might effect its performance, but that's a price I was willing to pay for not making my entire car smell like oxidized feline urine.
I have also used it indoors when my other cat was sick and peed on the floor in our previous apartment, but I didn't find it until it started to stink (behind some furniture). I completely soaked the spot in the carpet a couple times, very generously to make sure it got down to the pad. It removed the smell and I got my entire security deposit back.