Pre-purchase mechanism for autonomous vehicles

An onboard computing device of autonomous vehicle interacts with computers utilized by one or more merchants to enable users to pre-purchase items from the one or more merchants while en route to a destination. Merchant computing devices may employ dynamic promotions to incent the user to prep-purchase items and to reroute to a destination of the respective merchant. Once a user pre-purchases an item from a merchant, the merchant may prepare the item for the user's arrival by, for example, prepackaging the item, or manufacturing or assembling the item, while the customer is en route (i.e., before the user's autonomous vehicle arrives at the destination). The merchant computing device may send a pre-purchase confirmation to the onboard computing device of the user, which may indicate where the user's autonomous vehicle should park and/or where the pre-purchased items are being held for pick up.