"Coming up with ideas is interesting and indefinable, isn't it? The brain is a funny thing. An idea often emerges in the shower, or during a walk. Your brain has been ticking away and the idea just bubbles up. Occasionally you feel, 'God, I've gone dry.' It's like writers' block. Shortly before the launch of a new car, when I've used all my existing ideas, I think, 'Now what?' But running the car produces new ideas as you understand what you've created."