Somehow, faced with a white- knuckle ride round the chicanes of Goodwood Park, my lips can barely manage more than a manic grimace. By the time Michelle Mouton parks her Gucci handbag in the pocket of the fibreglass driver's door of the six-geared super souped-up Audi, I'm so tense my hair grip busts.
Michelle has been driving extremely fast cars since she was 14 and used to steal her father's for a quick spin round the cliff-edged streets of the south of France. She has beaten the world rally records in Brazil, San Remo, Portugal, Greece and the rally drivers ultimate, Pikes Peak in Colorado. She is, insists Stirling, one of the best. These days she only comes out for the Goodwood Festival of Speed, to keep her hand in once a year. The rest of the time she makes fast work of the school run and almost definitely holds the record for the quickest round trip to the supermarket in her home town of Antibes.
She is the only woman driver in the line up of 30 assorted cars; I think I'm the only woman passenger. We have no treads on the tyres ("treads slow you down") and the engine is revving so loudly my fillings are rattling. We look like a hardcore version of Thelma and Louise.
As the cars in front of us are waved through the start line, I prepare to go over the cliff. What have I got to live for anyway? Before I have time to go down that existential avenue, however, the engine roars off, my head is thrown back into the seat and I grip my legs so hard I puncture a hole in my favourite velour trousers.
I think I'm smiling - at least something is happening with my face - until I see the first wall. Nothing, not even Scream, can prepare you for the terror of approaching a stone wall at 150 miles an hour with a middle-aged French housewife at the wheel.
And then it's all over in a flash, or it would have been if I'd had my eyes open. We're round the 90- degree, left-hand turn and hitting it fast up the tree-lined hill. Trees, fast cars, dead film stars, it's amazing the things that go through your head. I try to turn against the pull of the G-force and sneak a look at Michelle. Her arms and legs are pumping and pushing like a fast forward Mr Motivator video.
If I were a real co-driver she'd be relying on me to bark out details from the in-car computer thingy. Mercifully this is just a dummy and the in-car computer thingy has been removed. Which is just as well as it's taking all my powers of concentration not to start screaming "I want my mummy".
Michelle says she got into rally- driving by accident. When she was 22, her father, probably tired of never being able to drive his own cars, bought her a Renault Alpine and told her to have a go. A year later she had won her first championship and never looked back. She says now that she can't imagine a better rush.
It's true, the injection of adrenalin is addictive. By the third death- defying turn I've almost managed to keep one eye open. Because the tyres have no grips on them the car moves around the road a lot, in an alarming, out-of-control, kind of way. But apparently this is normal. The car ahead of us is a 1961 Maseratti Birdcage, with the added fear factor of an open top.
Although I sometimes pose around in my 2CV with the top down, right now I realise it's just not in the same league as the big boy version. By the time we flash past the chequered flag I feel hysterical, overcome with my own sense of achievement. I have driven with the fastest woman in rally-racing, and survived. The engine is literally smoking.
I stagger jelly-legged from the car. Crowds of drivers, bystanders and officials are stepping forward to pat us on the back. "How do you feel?" enquires one. How do I feel? How do I feel? I feel, I reply, like Murray Walker should be spraying me with champagne. Move over, Stirling Moss.
The Festival of Speed, Goodwood Motor Circuit, 18-20 June.