GM's latest self-drive demonstration was thwarted by a lowly taco truck.

The demonstrations were for journalists at the media debut of the latest self-driving Chevrolet Bolt EV earlier this week in San Francisco. It was the first time for public road trips for non-employees in the cars.

In a 15-minute drive, the Bolt with Cruise Automation hardware and sensors traveled 2.2 miles. It encountered 117 people, four bikes, and 129 cars.

But while it could handle tram track rails, construction zones, pedestrian crossings, and even double parked cars, the autonomous Bolt EV was stopped by a taco truck. According to Reuters, the human driver was forced to disengage the system and drive around after the Bolt spent more than a minute unable to find a way around the truck.

Maybe it was just hungry? After all, who hasn't spent at least a minute trying to decide what you want at a taco truck? It was just a slight bit of heartburn for the self-driving Bolt, and it was able to finish the drive after that little help from its human friends.

At the event, GM President Dan Ammann restated CEO Mary Barra's previous promise that GM will introduce self-driving cars within "quarters, not years."