There're other ways to play up their 'not human' nature. Canon sources for Sylvie and Anri would tend to agree - they're more than capable of fitting in to the point where most people wouldn't notice them. Anri fits merrily into a corporate environment.
I love the smell of rotaries in the morning. You know one time, I got to work early, before the rush hour. I walked through the empty carpark, I didn't see one bloody Prius or Golf. And that smell, you know that gasoline smell, the whole carpark, smelled like.... ....speed.
One day they're going to ban them.