Motor impairment is frequently cited as a core characteristic of Autism Spectrum Disorder (ASD), yet its relationship with speech motor control remains underexplored. This study examined whether higher rates of speech sound errors in children with ASD stem from a single underlying motor impairment. Ten children with ASD and ten typically developing (TD) peers (ages 6-12) were assessed on nonverbal IQ, language ability, and gross and fine motor control. Speech motor control was measured using Diadochokinesis (DDK) tasks, recorded and analysed by ultrasound tongue imaging and acoustic analysis. Results revealed no significant differences between ASD and TD groups in DDK accuracy, rate, or consistency. However, TD children exhibited greater tongue shape variability in complex sequences, while ASD children showed reduced variability, suggesting rigidity in motor plans rather than impairment. Despite significant fine and gross motor deficits in the ASD group, these did not correlate with speech motor performance. Findings indicate that speech attunement difficulties, rather than speech motor deficits, may contribute to speech sound development challenges in ASD.