The woman had sustained serious injuries and was pronounced dead at hospital shortly afterwards.
A 52-year old man has been arrested in connection with her death.
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Two women, who were passengers in the car, suffered minor injuries and were taken to hospital for treatment.
It comes after officers last week renewed their appeal on the 20th anniversary of Michael Pritchard's death.
The OVO Energy Women's Tour race brought a £1.75 million boost to Northamptonshire's economy this summer.