POR QUÉ las furgonetas de UPS no giran a la izquierda:

UPS engineers found that left-hand turns were a major drag on efficiency. Turning against traffic resulted in long waits in left-hand turn lanes that wasted time and fuel, and it also led to a disproportionate number of accidents. By mapping out routes that involved "a series of right-hand loops," UPS improved profits and safety while touting their catchy, environmentally friendly policy. As of 2012, the right turn rule combined with other improvements -- for the wow factor, UPS doesn't separate them out -- saved around 10 million gallons of gas and reduced emissions by the equivalent of taking 5,300 cars of the road for a year.