A clanging hint, shall we say, that's echoing around the interior of my car like a steel drum in a crater. "Really?" I say, not quite believing my own ears. "That's exciting." The Oban-born racing driver smiles back, eyes twinkling. "I can't say too much about it just now because I'm fully focused on DTM," she says of the Deutsche Tourenwagen Masters (DTM), the annual internationally renowned German touring cars championship that Wolff has raced in for the past seven years. "But there's a strong potential."
It's a freezing cold morning just outside Larkhall, South Lanarkshire. Wolff, who is among the world's best female racers, has just finished posing for several rounds of photographs on the icy West of Scotland Kart Club (WSKC) track where she used to race as a child. Since there's nowhere warm nearby to have our interview, the 29-year-old has suggested we sit in one of our cars. And because her husband, Formula One investor Toto Wolff, is inside their stylish silver Mercedes making a phone call, we have to plump for my slightly shabby-looking black VW Polo instead.
So that's how we got here – in the front seats of my less-than-clean car in the middle of a gravel car park in Larkhall. And that's where she dropped the bombshell, while talking about her ambitions for 2012. "I think every driver's goal is F1 because it's the pinnacle of driving. It doesn't get any higher or any better or any more technologically advanced," she says. "My targets and goals are very much still in DTM but I want to drive an F1 car and it's something I think will happen, definitely. I think the F1 thing will happen this year."
If it does, she will be one of only a handful of women to step inside an F1 car since Italian racer Giovanna Amati briefly competed in 1992. She'll also be one of the few females who have test-driven an F1 vehicle for genuinely competitive rather than publicity reasons.
Wolff is remaining tight-lipped over any details about how, when and with which F1 team, and says only that she thinks she will be allowed to complete a test drive in one of these cars this year.
"I'm not dreaming of a F1 career, to be F1 champion," she admits. "I just want to have a test. There have been many opportunities to do it before as a marketing and publicity stunt and I've always turned it down. I've got where I am by being a racer, not by being a female. The two goals this year are to score podium places in DTM and to do an F1 test. If I can achieve these goals by the end of 2012, I'll be happy."
Wolff – known as Susie Stoddart until her wedding at the end of last year – is in a good place right now. Even excluding those F1 expectations, her driving career in highly engineered Mercedes cars in DTM seems secure and looks set to become more competitive. And then there is her marriage to long-term partner Toto, an Austrian former racing driver and an investor in the Williams F1 team. "I always tell people he's my biggest supporter but also my biggest critic," she says. (He's also a terrible passenger, she adds.)
Wolff started racing aged just eight and, like most successful drivers, spent many of her formative years track-side. Her mother is a long-standing motorsport fan; her father, John Stoddart, owned a motorcycle dealership in Oban and competitively raced bikes. Wolff, alongside her older brother David, spent countless weekends watching her father compete before deciding to give kart racing a go herself.
"I was always very competitive," she says. "I did a lot of skiing and swimming when I was younger, but the karting was my main focus. I was never pushed by my parents, it was never, 'I don't want to go.' It was: 'Let's go, let's go.'" Despite the family passion for motorbikes, she has never raced on two wheels. "A bike licence is too dangerous," she says. "My dad won't let me have one."
He did, however, let her compete as a child and then a teenager in karts, where she raced in the British Championship, the European Championship and the World Championship. She then earned her place in Formula Renault where she achieved numerous podium finishes before moving on to Formula 3.
Aged 13, while still karting, she attended an F3 race at Donington Park. After watching Jenson Button win, she said: "That's what I want to do."
"I think joining Mercedes-Benz and DTM [which she joined after leaving F3] was definitely the best day of my career and I really want to stay with Mercedes-Benz long term. I really want to drive an F1 car, test the car, but very much score a podium in DTM and be successful in DTM and see what comes after that."
Wolff joined the DTM series in 2006, and has raced in one of the specially engineered Mercedes cars ever since. The season, which this year spans 11 races and includes tracks in Spain, Germany and Austria besides Brands Hatch in the UK, starts at the end of April and runs until October. Despite a number of women entering the tournament in the last decade, Wolff is one of only two female drivers who race in the German championship, the other being Swiss 26-year-old Rahel Frey who competes for Audi.
"I'm in a man's world for sure," says Wolff, who hates the idea of being a token female in any line-up. "I don't want to be in a man's world and only there because I'm something different. I want to stand on my own two feet and be independent and compete against the guys."
Here on the WSKC track, half-a-dozen young men dressed in race suits are waiting to go out in their karts. Wolff will drive a few laps too and, as is often the case, she'll be the only female on track. Does that bother her?
"It doesn't help that my car was pink last year and in the past two seasons in DTM," she replies, laughing. So she didn't choose the bodywork of her V8 AMG-Mercedes? "Choose that? No, it's all marketing."
Wolff loves fashion and admits to a weakness for handbags, but she is determined to be in motor racing for her own talents and not because, with her blonde hair and photogenic looks, she is a marketing manager's dream.
"I think because I've been there so long [in DTM] and also because at the beginning I kept my head down and earned the respect from everybody, that I'm accepted inside the Mercedes-Benz team now," she says. "Norbert Haug, the head, gave me a massive chance when I was up and coming to bring me into DTM. He says, 'Susie's not with us because she's a girl, she's with us because she's a racing driver.'"
Wolff knows, however, that many of the male drivers do see her differently and more importantly, compete against her on different terms.
"Within my team it's always clear to me that the guys do not like to be beaten by a female. It's an ego thing. I think most racing drivers, especially successful racing drivers, are egoistic – they're always out for themselves and the thought of being beaten by a female in a pink car is quite hard to take."
Though she is always focused on the track, Wolff knows from teammates that sometimes, competitors will speed up when they see her pink car ahead. "It's such a cliche – a blonde girl driving a pink car," she says. "For me being successful in the car is the main thing."
Wolff lives with her husband in the Swiss town of Ermatingen on the banks of Lake Constance, and speaks fluent German. Her Oban accent is fading. "It's a shame my Scots accent is going a bit, but Switzerland is home now, though I don't see myself living there for ever."
Her fluent German is a measure of just how focused Wolff is on her racing career. After being signed to race in DTM in 2006 she immediately began learning the language to converse with her Mercedes-Benz team-mates in their native tongue.
"Working for a German car manufacturer, I think it's only polite that you speak their language," she says. "I studied German at school, then took lessons when I joined Mercedes-Benz while still living in the UK. Then I moved over to the German-speaking part of Switzerland. The first three months were difficult not knowing the words, but then it comes really quickly because you have to."
Wolff lives her professional life, as the cliche would have it, in the fast lane. She thrives on the environment. "It's the adrenalin kick, the competitiveness, the trying to get the last 100th or 10th out of yourself on the race track that I love – it's a challenge."
Wolff has had to train hard to put herself on a level playing field with her male competitors. "I have to do more weight training and body training than the boys because guys have 30% more muscle than women," she explains. "It's tough but it's doable. Anyway, I'm disciplined and I enjoy doing sports, so it's not a big hassle to get up in the morning and go to the gym."
Those gym visits are essential. "People don't realise quite how physical it is in the cars," she says. "There's a lot of forces going through the body. You have to stay concentrated even when it's very hot in the car with no air flow and you're sweating.
"Your upper body, particularly the neck, is important as there are a lot of G-forces [the gravitational pressures exerted during acceleration] running through it. At the end of the season I'm always exhausted and looking for a break.
"But now I've had the break and I'm ready to go again." And with that, Susie Wolff heads back out on to the track.