The former BP staff driver, now 91, was “giggling like a wee girl” according to granddaughter Ellen Birt, as she became the Fife circuit’s oldest female driver, if not oldest overall.
Clark, who regularly drives from her Stonehaven home, was praised by her instructor for having a “really good racing line” when cornering at Knockhill on Friday – but she said she had been too busy looking at the track to notice what speed she reached.
However, her granddaughter confirmed: “She definitely got a pace up on the straights.”
Clark said she would now love to show the E-Type’s owner, former rally champion Bob Watson, what the car could do “on the straight roads of Deeside”.
She told Scotland on Sunday: “It was fantastic. I felt quite safe.
"I had a very experienced ex-racing driver with me, who was great.”
Clark is now even considering a sky diving trip to mark her 92nd birthday - but as an arthritis suffer, joked that she “would have to think about that one seriously”.
Her Knockhill trip was delayed from last year by the Covid pandemic, but it gave her something to look forward to during months of having to shield on her own.
Birt said: "My gran has an absolute zest for life and always made our birthdays really special, with mad activities.
"When she turned 90, she’s not the type to take out for afternoon tea, so I thought about what we could do that she’s never done before and she would absolutely love.
"She’s a really good driver and has taught her own children and friends to drive over the years, but she’s never been in a race car.
"So for her 90th birthday, my gran, of all people, would be the person that wants to hit the race track.
"The opportunity to go in a classic E-Type Jaguar just seemed like a complete meeting of minds.
“When she opened the envelope with the details, she said “I can’t wait’.
“She was up for it from the word go.”
Birt also praised the “fantastic” team at Knockhill for making the occasion “an exceptional day”.
She said: “There was never a question that they wouldn’t get my gran round the track.
"They were so supportive and excited about her coming, and the day was so special.”
Clark was then taken round the track by another instructor at racing speed, during which she felt like a “starfish glued to the back of the seat”.
Birt said: "My gran and I are now concocting what she’ll do when she turns 92 [in January].
“We both threatened my mum we’ll go sky diving.
"My gran said immediately, without missing a beat, ‘I’ve always wanted to do a sky dive’."
But if that doesn’t work out, Clark might get behind the wheel of an even faster car at Knockhill.
“We were looking at a Ferrari going round the track and reckoned she could do that next year," Birt said.