Still on the colorful subject of brand-building and the inseparable role of color, I found an excellent reference source, via Martin Lindstrom, Brand Strategist, and his books “Buyology” and “Brand Sense”.
… John Hertz had a small stake in a car dealership in Chicago with a surplus of used cars. He hit on the idea of turning them into taxi cabs.
At some point Hertz heard about a University of Chicago study that revealed that yellow was the easiest color to see, and so he had all these cars painted yellow, and called the company Yellow Cab.
… When Hertz sold out, he went on to form Hertz Rent-a-Car and again made yellow the cornerstone of the new company’s logo.