I once interviewed a guy who started the interview by saying "I have Asperger's and I'm just letting you know because I'm not good at social skills, but it's not a problem in my work performance." This was years ago, before I started studying ASD. I really appreciated his honesty and it explained his quirks, which, yes, I picked up on right away.
But even then, I would have hired someone with AS over someone who was NT and had, say, self esteem problems, or didn't really want the job. I might have assumed one of those things if he hadn't disclosed his AS to me. Managers are TRAINED to look for things like eye contact, how you sit, your tone of voice, etc. which most people with ASD cannot help. The "autistic look" has been often described as "aloof" and this is NOT what you want in an employee. But if you know that the person does indeed care about the job, no matter what their body language says, this goes a long way.
I didn't hire the guy because he had all the wrong skills for the position I had open and I didn't have anything coming up that I could have moved him to. But I say if you know you have problems in an interview, just tell them you're on the spectrum and then give them your own definition of what that means.