12/04/2013 18:14 BST | Updated 12/06/2013 06:12 BST

My Sister, the Formula One Driver

Let me introduce myself, I'm Susie Wolff's older brother David Stoddart. I am a film maker and Susie is a female racing driver. These two things don't normally go together and that is why the question I am always asked is: "How did your sister end up being a racing driver?"

For Susie, it all started as a young girl. We had motorsport in our blood as my mum met my dad when she went in to his motorbike shop to buy her first bike. We always followed my dad around as he raced bikes and Susie and I would spend most of our time driving the little karts behind the main racetrack. Eventually my dad stopped racing and bought us both proper karts and that is when her journey really began. By 13, Susie dreamt of being a F1 driver.

Dreams do come true. At 30, Susie is a development driver for the Williams Formula One team and had her first F1 test last year. Susie trusted me to film over a year of her racing life for my documentary Driven: The Fastest Woman in the World filmed over a year of Susie's racing life, including her testing for Williams.

Driving out of the pit lane for the first time was a dream coming true for Susie. I obviously enjoy watching her drive, it makes me incredibly proud, although that doesn't mean that I don't get nervous at the beginning of each race, but I have so much confidence in her ability so I know she'll be fine. I know how good she is.

Susie loves the adrenaline, the speed and of course the competition. Nothing can match the feeling of success and nothing can be as hard to take as the disappointment of losing. Susie can be quite a guarded person so at times it was difficult as when she was dealing with some of the low points leading up to her Formula One test, she obviously didn't want a camera crew around documenting her tough times. It was my natural instinct to step in as a brother and try to make things better, but as a filmmaker I had to stand back and leave things in the hands of her team.

As her brother, I was given a level of trust that not many other filmmakers would have been granted. Susie was very open and honest throughout filming as she knew that I wasn't out to do some expose on women in motorsport; instead I was aiming to tell her story and prove that she's not on a crusade to show that women can compete against men on the racetrack. She's following her life-long passion and doing what she loves.

Many people have the perception that motorsport is glamorous, but behind the scenes it is actually incredibly tough and competitive. I hope my BBC documentary Driven: The Fastest Woman in the World will give a rare glimpse into Susie's life, as a woman, in Formula One.

Watch Driven: The Fastest Woman in the World on 14 April from 5.30-6.30pm on BBC2