One ambulance and police were called to the car park at around 12pm, which is just off Carpet Trades Way.
The drivers window was immediately covered up and the area of the car park, just outside of Staples, was cordoned off for around two hours on Wednesday afternoon.
Staples worker Sarah Darby said: "It was a bit of a commotion, police had cordoned off this part of the car park. It was all a bit of a shock, you don't expect something like that to happen at all.
"We couldn't see much but it looked like police and ambulance were doing their best."
West Merica Police spokesperson Connie Osborne said: "Police are treating the death as unexplained but it is not thought to be suspicious at this time.A post-mortem examination is yet to be conducted.Enquiries are still ongoing."