From The Sun Online:

[...] he looked across at James May and said: “Hello C**k face.”

The idea to drive a jet car actually came from Hammond. He skedaddled into the office one day and, bubbling with his trademark enthusiasm, said: “Hey, why don’t we go somewhere and drive really fast? I don’t mean supercar fast. I mean REALLY fast.”

From what I understand, you sit there, you push a lever to light the afterburner and you then push another to shut off the fuel supply — it runs on heating oil — and deploy the parachutes. A hamster could do it. In fact, a hamster did.

After the crash:

“I want to do a piece to camera”, he told the crew. He even fought the ambulancemen, who said he couldn’t. No surprises there. Richard likes fighting. He does it a lot.

Clarkson also replies to the accusations that the show’s producers pushed them to do these kinda stunts. A very good read.