The day before the incident last July another woman loading her BMW in another supermarket car-park was also threatened by a man holding a baseball bat above his head who ran off.
Mark Henry, 26, of Kilburn, north-west London, denies affray at Waitrose in East Sheen, south-west London, and attempting to murder and causing grievous bodily harm to Doris Thompson, 45, at Sainsbury's in Wandsworth, south London.
Orlando Pownall, for the prosecution, told the Old Bailey that Mrs Thompson, of Belgravia, central London, was lucky to survive the 'ferocious attack'.
An assistant at Sainsbury's in Wandsworth was also hit by Mr Henry, who was blocked by other shoppers when he tried to drive off in the BMW and escaped on foot, it was alleged.
The trial continues today.