The original details in this story were not correct. The person driving the Porsche was a mechanic, according to The Mirror from the United Kingdom.
There's nothing unusual about wanting to get experience car before buying it, but the test driver of this Porsche 911 takes that experience a bit too far. The ride ends with the expensive sports coupe in pieces.
The driver takes the corner going way too fast, and unfortunately another car is coming down the road. If the other vehicle weren't there, the Porsche might have successfully negotiated the slight S-curve. Instead, the 911 clipped the side of the oncoming sedan and started spinning, including tearing off the rear bumper. A high curb potentially helped the German sports car's pilot. Instead of the driver's door smashing into a pole, the barrier kept the 911 on the road.
Neither the two passengers in the Porsche nor the sedan's driver were injured in this crash. We suspect the vehicles aren't so fortunate, though. The serious damage to the 911 likely makes it a write-off. The other vehicle appears in better shape, but if there was serious frame damage, it could be totaled, too.
Given the existence of this video, the dealer's insurance company would probably want to have a word with the Porsche's driver. The person would likely have a hard time arguing that the crash was an accident given that the clip shows the 911 entering the corner at such a high speed.
If it's any consolation to the driver, a new generation of the 911 should be available soon for the person to take a more sedate test drive in. Spy photos suggest an evolutionary aesthetic upgrade with additions like LED taillights across the entire rear, taking a cue from the Mission E concept.