No 5-star rating for this Uber driver! He delivered a heavyweight punch to an elderly passenger — reportedly for one simple reason: not enough legroom.

Caught on surveillance camera in Dallas Wednesday … the Uber driver picks up a couple, but doesn’t hit the road right away. A few minutes later, he pops out of the car at the same time as his passenger, 68-year-old Suleman Gauba, and viciously jabs him in the back of the head — so hard, it sends Gauba crashing to the ground.

The Uber driver looms over Gauba as his wife rushes out of the car to witness the shocking scene.

Gauba, originally from Pakistan, later told Fox 4 that since moving to Dallas, he’s been relying on Uber to get around — and on this occasion, all he and his wife wanted was a trip to Walmart.

Instead, things took a turn when Gauba complained the back seat was too cramped. That apparently sent the unidentified driver into a rage, and he canceled the ride. When Gauba pushed back, and his wife said she was calling the cops, all hell broke loose — that’s when the assault occurred.