In this case, likely the car would have shot out across the footpath, the road, the far footpath, and etc. possibly hitting someone on the path, or a vehicle driving along the road. So I can see why he would've tried to stop it, even at the risk of his own life - if that was what happened.
The car ended up, at an angle, nose towards the wall - which suggests he managed to pull the top of the steering wheel towards him, as it progressed down the drive - again, if that is what happened.