The Colorado State Patrol says it happened around 3:30 p.m. when a boulder about the size of a pumpkin, or 2 to 3 feet wide, rolled down the hillside.
The boulder hit a 2006 Honda Accord being driven by 53-year-old Kurt Kuxhausen at mile marker 125 near Glenwood Canyon.
It hit the rear passenger door between the top of the door and the roof and the car was totaled by the damage.
Despite the damage, Kuxhausen was able to drive the car home to Grand Junction.
The boulder came down in the same work area as the massive rockslide on March 8 that damaged the road and closed the highway for several days.
CDOT says repairs are still going on and the weather has caused several boulders to continue falling on the road.
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