It’s been a turbulent year for Elon Musk but it ended on a high—or, rather, a low—when he opened his first underground tunnel, designed to give commuters a chance to avoid Los Angeles traffic. Invited guests were given the first chance to experience the subterranean tube Tuesday night, traveling via a Tesla Model S for about a mile. An elevator lowered the electric car 30 foot underground and demonstration rides went through the tube at 40 mph, but Musk says vehicles could eventually travel through at 150 mph. “Once a light at the front of the tunnel turned green, the car was off like a roller coaster,” The Washington Post reports. “The proximity to the tunnel walls made it seem like it was going much faster; white paint and blue lighting along the top of the tunnel made the ride feel more like a music video than Batman’s cave.” The ride was a bumpy one, but Musk said he’d run out of time to smooth out the test tunnel’s concrete base in time for the event.