This is the outline of the upper torso and two arms with the addition of two hands. It is an ideograph for activity involving the use of both hands and thus an element of control. Therefore, Mahadevan's sign number 1096 is the verb to drive.
Illustrative Text Reference:
Mohenjo-daro: Seal: M-307 a: Jagat Pati Joshi and Asko Parpola, 1987: Corpus of Indus Seals and Inscriptions: Volume 1: Page 76: Collections in India: Suomalainen Tiedeakatemia.
Image Credit:
Indus Script Sign Number 1096: List of Sign Variants: Iravatham Mahadevan, 1977: The Indus Script: Texts, Concordance and Tables: The Director General Archaeological Survey of India.