Les Jackson
AIADA Contributing Editor
Throughout history all societies have embraced beliefs that eventually were proved to be untrue. Even in this modern era with its printed, broadcast and internet sources, many people still believe "truths" that are, in fact, incorrect. Some of these urban myths involve the automobile and it's time to separate the facts from fiction. Take a look at these popular myths
Truth: Octane-boosting substances in gasoline actually retard the burning rate so that the heat of compression won't pre-ignite the mixture, causing "knock" or "ping." There is no measurable performance improvement to be gained by using higher-than-specified octane fuel in your car. The engine's compression ratio primarily dictates the octane requirement, along with some internal component designs, and manufacturers always show the grade of fuel required for each model. Using higher octane fuel in an engine designed for lower octane simply wastes money and can result in less complete combustion, resulting in lower fuel mileage.
Truth: Octane content is basically the same as it always was, but the numbers are lower. That's because there are two methods of measuring octane level: Motor and Research. Gasoline used to be rated solely by the Research method, which yielded higher numbers than the Motor method. Today's fuels use an average of the two and are therefore numerically lower. 100 Research (RON - Research Octane Number) is 94 octane in today's rating system. Octane levels used to be managed with the addition of Tetraethyl Lead. Lead was phased out in the 1970s and gasoline now is mixed with less harmful substances such as methyl and ethyl alcohols.
Truth: Many, many heard this story in one form or another. It seems a neighbor of a friend of a friend, etc., knew of a man who bought a new car (variations of the story range from the 1940s to the 1970s). Shortly after taking delivery he noticed that the car was getting fantastic gas mileage (some stories say 50 mpg, some say as much as 200 mpg!). His fuel gauge didn't move from the full mark until he had traveled many miles, so he opened the hood to see if something might be wrong with his gauge wiring.
What he saw after removing the air filter was a strange-looking carburetor. In fact, it didn't look like a carburetor at all, but rather like a "black box." He kept driving the car for a few months and found he continued to get fantastic, unheard-of mileage. As the story goes, he was eventually contacted by a factory representative who showed up at his house and explained that an experimental carburetor was inadvertently installed in a production car and sold to him, but the factory wanted it back. Discussions ensued, with the result that the owner of the car got a top-of-the-line car in trade, plus some cash as long as he signed a non-disclosure agreement.
This story never happened and no manufacturer ever developed such a carburetor. If a super-efficient carburetor could have been developed it would have been. Engineers wouldn't have moved over to sophisticated electronic fuel injection and engine management systems if they could have accomplished the same thing with a carburetor. Automakers wouldn't be working so hard today to increase mileage if there were a simple solution to achieving it. Weight savings, sophisticated cylinder firing systems, hybrid drivetrains, etc., all exist to squeeze every tenth of a mile they can out of a gallon of gas.
Truth: The pressure stamped on a tire's sidewall is the tire manufacturer's maximum inflation level for safe driving in all conditions. It is not the "normal" inflation pressure and would be too high for everyday driving. The correct pressure can be found on a tag either in the doorframe area or glove compartment lid in your vehicle. The pressure is determined by many factors including the vehicle's weight, load-carrying capacity, operating parameters, fuel economy and speed potential. Tire and auto manufacturer's engineers work very closely to arrive at optimum pressure levels for overall conditions and maximum tire lifetime.
Truth: Actually, this practice was never really recommended by manufacturers. All automotive engineers will tell you that the most effective way to warm up a car is to drive it. All components get to desired operating temperature at similar rates and exhibit the least wear. The warm-up myth came about due to the practice in northern climates of pre-warming the cars in the winter so that the heater could get the interior comfortable before starting out. It was further popularized in the early 1970s when emissions regulations led to lean-burn carburetors. Engines tended to balk and stutter when cold, causing owners to warm them up before driving. Today's engines are designed to start and warm up quickly and should be driven right away for best emissions levels.
Truth: We all know people who say that red or yellow cars get more speeding tickets than other, more modest colors, but police departments around the country say that this is not true. They say that they ticket according to the nature of the offense and conditions at the time. Also, insurance companies don't have rates indexed to vehicle color. If it were true that red and yellow cars receive more tickets the insurance companies would certainly have different rates - just as they do for sports and high-performance vehicles.
Truth: While long known as a destructive practical joke, pouring sugar in the tank is supposed to gum-up the fuel system and destroy the engine. In fact, sugar doesn't dissolve in hydrocarbon fuels so it would simply sit there harmlessly in the bottom of the tank. If enough were poured into the tank so that the fuel pump sucked it into the lines the fuel filter would simply clog up.
Truth: The Corvair was vilified by Nader as a death trap in his 1965 book, Unsafe At Any Speed, but GM had made the decision to cease further development on the car one year earlier. The reason was the Mustang! In 1964 GM executives realized that the sporty, easy-to-option Mustang presented a competitive challenge impossible to overcome by the Corvair and its rear-engined configuration.
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