A worker was behind the wheel of a £200,000 McLaren supercar when it came off the road on the A285 in Duncton on Friday.
The employee was driving the McLaren 650S back to the McLaren factory when it left the road and overturned.
The man was airlifted to St George’s Hospital in Tooting.
A spokesman for Sussex Police said the man was ‘impaled’ on a fence post.
His injuries are described as life threatening.
McLaren has not yet provided the Chichester Observer with a statement, but other sources say employees permitted to drive the cars have to pass an intensive driving course before they are allowed to drive.
Police, ambulance and fire crews worked to free then man from the wreckage.
The Mclaren 650S has a top speed of 207mph.
Police are appealing for anyone who saw the incident to call 101 or email Sussex Police quoting Operation Adstone.