I think this topic has a lot of mixed opinions when this is discussed. There's a lot of horror stories about wiring harnesses, alternators etc. My opinion is if you're careful and cover the alternator with a plastic bag and avoid computers and don't aim your fire at those areas you should be ok. Just be careful. A steam cleaner to me is also is a bit more easing in my mind than a pressure washer anyway for some reason. Then whatever you miss with the cleaner, wax on wax off hand technique will go a long way.