The serious crash happened at around 7.20am on Saturday (March 16) when a black Volkswagen Polo travelling along Cold Ashby Road, for reasons unknown, left the carriageway and came to rest in a field, between Cold Ashby and the West Haddon/Guilsborough Road junction.
The male driver was taken to University Hospital Coventry by air ambulance with potentially life-threatening injuries.
A spokesman for the East Midlands Ambulance Service said: "We sent a paramedic in an ambulance car, a crewed ambulance and the air ambulance. We transported one patient to University Hospital."
Police investigating the single-car collision are appealing for anyone with information to get in touch.
Anyone with information or who witnessed this incident is asked to call the Drivewatch Hotline on 0800 174615.
