Kristen Stewart is happiest when she is driving.

The 'Snow White and the Huntsman' actress - who is dating her 'Twilight' co-star Robert Pattinson - is at her most contended when she is away from film sets and listening to music in her car.

She said: "When am I happiest? In my car with the right friend -- I like to drive and I love being in Los Angeles, it always feels like, 'Ahhh.'

"So I would say if the right song came on, windows down, that's a great feeling. To just be exciting to be moving, to be like, 'Here we are.'

However, she does have long-term plans in the movie business and expects she will direct a film one day.

She added: "I want to direct movies. Sometimes I think, 'God, I want to do that, I want to do that next,' but then I work with someone who's great at what they do and I think, 'I'm not there yet.'

Discussing her best time on the film-set, Kristen admits her debut in 2002 movie 'Panic Room' with Jodie Foster is still her favourite.

She said: "I was really lucky. Jodie's incredibly professional but she's not too professional because she's so cool.

"She's just another member of the crew. I love that and it's completely influenced me."