You obviously don't live in Los Angeles.
The solution is not to force urban sprawl. The problem here is that everyone lives far away from where they work (due to rent prices in various neighborhoods), this forces the majority of the working middle class to commute to more affluent neighborhoods for jobs. If you minimize population density, you maximize commute distances.
The solution is the opposite, you need to create affordable living even in affluent neighborhoods, so that fewer people are using the highway to commute to work. Thats not to say you need a highrise apartment on the same block as the Beverly Hills Mansions, but if there was affordable apartments in the area, you wouldn't have all those maids and other workers commuting on the highways.
This is all compounded by the fact that only a portion of the traffic in Los Angeles is local, there are constantly thousands of tourists and tons freight moving on the highways. Ideally you organize the city so that locals don't need to use the highways as often.