Kevin Hart was definitely a passenger in the car crash that landed him in the hospital ... we know that because our law enforcement sources tell us the physical evidence proves his friend was behind the wheel.
Our CHP sources tell us ... Kevin's friend, Jared Black, was indisputably driving early Sunday morning. They know that because we're told he was trapped in the driver's seat in such a way that the firefighters had to literally cut the wreckage around him to extricate him from the vehicle.
We're told Jared also had injuries consistent with a steering wheel impact.
Our sources say both Jared and Kevin had back injuries, and they believe it's because the car did not have seat belt harnesses. The car -- a 1970 tricked out Plymouth Barracuda -- only had lap belts and, when there's a forceful impact, it often creates serious back injuries because the body lunges forward.
TMZ broke the story ... Kevin had 3 spinal fractures in the lumbar and thoracic areas, and surgeons fused the vertebrae. He will remain in the hospital at least through the week and will have to endure a very long rehab. He's currently in extreme pain and heavily medicated.
We got shots yesterday of the accident scene in the Malibu area, where CHP officers were taking measurements. We're told they neglected to do that the morning of the accident and were doing belated due diligence.
We're told there is no criminal investigation.