A Mazda SUV equipped with an automatic-braking system crashed in Japan last Sunday during a dealership test drive, injuring the driver and front-seat passenger, according to the police.

The Mazda CX-5 was being driven by a prospective customer on the dealership’s parking lot when it crashed through the urethane barrier set up to demonstrate the SUV’s automatic braking technology, according to the Saitama Prefectural Police, which is investigating the accident.

The customer suffered a neck injury while the dealership employee sitting in the front passenger seat fractured his arm, the police said. Mazda is investigating the case, Makoto Watanabe, a company spokesman, said by phone today. He couldn’t confirm whether the model being tested at the dealership had the brake feature.

“For any safety function, its impossible to be 100-percent free of accidents,” said Hiroshi Ataka, a Tokyo-based auto parts analyst at IHS Automotive. “These technical functions aren’t always the easiest to understand.”

Mazda’s automatic brake system, called Smart City Brake Support, uses a laser sensor to detect obstacles in front of the car to avoid or mitigate the impact of collisions by automatically applying the brakes, according to its website. If the driver accelerates when an obstacle is detected, the system is designed to sound an alert while curbing engine output to stop unintended acceleration.

When the CX-5 was introduced in February 2012, Mazda offered the auto-braking technology as an optional safety feature for an additional price, before making it a standard setting for the model after it was refreshed in Japan last month, according to the company.

“We will fully cooperate with the police investigation upon request,” said Watanabe.