Police officers often mistakenly assume that lights and sirens will make the police vehicle invulnerable, but this is not the case. Warning lights are not always visible to others. A study by the Illinois State Police showed that vehicles without lightbars had better fuel mileage, 25 percent better productivity in speed enforcement productivity, and 65 percent fewer accidents per million vehicle-miles. The National Bureau of Standards has determined that red lights mixed with white are the most noticeable, followed by blue and white. However, many types of vehicles use warning lights, and most do not represent a signal to a motorist to pull over and stop. Thus, motorists can become confused about whether to get out of the way or whether to stop. Police officers also need to know when to use warning lights. The National Bureau of Standards recommends using them to transmit a message to the public. Flashing lights and revolving lights would have different meanings. A consistent message policy should be instituted locally, statewide, and even nationally. Photograph.