In PWP-003, Brownstone and Lave forecast transportation energy demand, for both the U.S. and California, for the next 20 years. They focus on the largest segments of the market: gasoline, jet fuel, and diesel. Their forecasts emphasize variables that can be predicted with comparatively high accuracy, such as demographics and time trends, while downplaying the influence of factors that can be predicted with only a high degree of uncertainty, such as relative fuel prices. They argue that gasoline demand will grow at a slower rate than it has in the last two decades because vehicle ownership is becoming saturated. Jet and diesel fuels are forecast to grow at slightly lower than current rates. Overall, they predict that transportation petroleum demand will grow considerably more slowly than during the last 20 years, suggesting that rapid conversion to alternative fuels cannot be justified by demand pressure.