Autistic artist Stephen Wiltshire drawing New York City from memory:
When I interact with ASD individuals, many become frustrated by the myths that abound about autism. One of the most commonly mentioned is the assumption by many that if a person is on the spectrum, he must have some unusual (savant) skill.
Savant syndrome is a relatively rare but remarkable condition in which an individual with significant disabilities also shows "an island of genius" in a specific area.
Statistics about how common this phenomenon is vary depending on how a savant skill is defined. Some reports indicate that as many as 10% of individuals on the spectrum show some degree of exceptional ability (including "splinter skills"). These skills include an "obsessive preoccupation with, and memorization of, music and sports trivia, license plate numbers, maps, historical facts or obscure items such as vacuum cleaner motor sounds, for example" (Treffert, 2009).
According to Treffert, about half of savants are autistic, and half have other developmental disabilities or neurologic conditions (even acquired injuries or disease). When describing prodigious savants (a term used for the most advanced savant abilities), perhaps 100 living individuals are identified. Very few female savants have been described (6:1 ratio of males to females).
Interestingly, savant skills generally occur within a limited number of categories and include some degree of prodigious memory skills (e.g., photographic memory). Five identified types of frequently described savant ability include music, art, calendar calculating, mathematics, and mechanical or spatial skills (e.g., measuring precise distances by eye).
When it comes to cognitive skills (even in the absence of savant skills) many, if not most, individuals on the spectrum show "uneven" abilities (DSM-5 manual). For example, whereas the neurotypical individual would likely show a fairly even ability level (e.g., generally average or generally below average), the spectrum individual is likely to show some skills much higher or lower than others. It is the uneven nature of the skills that is common in autism, rather than any specific pattern of highs and lows.
To read more about savant skills, you may wish to investigate Treffert's work --
Treffert DA. The savant syndrome: an extraordinary condition. A synopsis: past, present, future. Philos Trans R Soc Lond B Biol Sci. 2009;364(1522):1351–1357. doi:10.1098/rstb.2008.0326