HOPEWELL TWP. — A lucky motorist escaped with his head — and his life — yesterday when his little Hyundai ran under a tanker truck on Route 31 and was scrunched to a crippling halt.

Ernest Tkac, a retired engineering drafting salesman who lives in Bucks County, Pa., confounded alarmed witnesses when he stepped out of the car unscathed, a smile on his face.

Police shook his hand, a news photog snapped pictures of the miracle in progress, and a reporter told him it was good to still have him around.

“Sometimes we get lucky,” said township Police Chief George Meyer.

Both vehicles had been heading north on Pennington Road (Route 31) here near Crest Avenue at about 3:20 p.m. The huge tanker, apparently loaded with municipal waste and operated by Gary W. Gray Trucking of Delaware, N.J., was in the passing lane, while Tkac’s Hyundai was in the right-hand slow lane.

For some reason, Tkac apparently made a left turn and disappeared under the tanker! The belly of the truck was actually tall enough in the middle for the Hyundai Elantra to get under it. But the back wheels of the truck began wedging the car, and denting it, dragging it under there for perhaps 30 feet.

“It got wedged underneath, that’s all,” said a police officer who gave Tkac a ride to Colonial Cadillac/Hyundai afterwards. “He walked right out. I drove the car right out from under the truck.” And the undamaged truck drove off.

Tkac was ticketed for failure to keep right. He was last seen at a desk in the dealership talking to his auto insurance carrier — apparently preparing to buy another Hyundai to replace his totaled car.

“Good car,” he said. “One of the best cars in the world.”

To a customer eyeing the new Genesis coupe, Ernie exclaimed, “Buy two of them, one for you, one for your son!”