Data is great, but personally I'd argue that Spock is probably more strongly autistically coded than Data. Vulcans have more intense emotions than humans (hence why they suppress them) and that parallels well with the intensity of the autistic experience at times. I am also reminded of the scene at the start of Star Trek IV: The Voyage Home where Spock (having just finished his re-education post the events of Star Trek II & III) discusses emotions with his human mother, indicating that Vulcans don't always understand what they are feeling, either.
Another good example would be Spock's father Sarek - particularly the TNG episode featuring him, where his illness results in a breakdown of his normal self-control. Picard volunteers to take the cognitive load of Sarek's emotional control so that Sarek can complete some key negotiations, which is the only time we really see the strength of Sarek's feelings; again one could look at this as a parallel to the internal autistic experience that is difficult or impossible to express to the outside world.