"Motorcycle X has been manufactured in the United States for more than 70 years. Although one foreign company has copied the motorcycle and is selling it for less, the company has failed to attract motorcycle X customers-some say because its product lacks the exceptionally loud noise made by motorcycle X. But there must be some other explanation. After all, foreign cars tend to be quieter than similar American-made cars, but they sell at least as well. Also, television advertisements for motorcycle X highlight its durability and sleek lines, not its noisiness, and the ads typically have voice-overs or rock music rather than engine-roar on the sound track."


The author's argument that must be some other reason to explain why the foreign company has failed to attract motorcycle X customers is flawed. In drawing this conclusion, the author not only assumes that motorcycle customers look for the same characteristics in a motorcycle as car customers do, but also assumes that the relationship between American and foreign cars is a good evidence to explain that the loud noise is the reason for the foreign company sells fail.
Firstly, the author bases the conclusion on an assumption that motorcycle customers and car customers share the same opinions in relation to both vehicles without presenting reasons for this thought. If, for example, a motorcycle customer is buying a motorcycle to enjoy it as a hobby, he might want a vehicle that makes him feel like a pilot. In this case, the loud noise can be a desirable quality. Conversely, if a person wants to buy a car to use it only for daily locomotion, she might prefer a car, which is more comfortable and less noisy. Since the author does not present any information regarding customer's motivation to buy a motorcycle or a car, the author's conclusion is flawed.
Secondly, the argument assumes that the comparison between the noise made my foreign-made cars and American-made cars is a measure to explain his conclusion. However, if customers of cars and customers of motorcycles do not share the same motivations when they are deciding to buy a car or a motorcycle, the argument fails. Foreign cars might sell at least well in the US because its customers want a car for long trips, and they prefer the comfort of a car than the adrenaline of a motorcycle. In this case, a quieter car is more attractive. On the other hand, people who like to drive a motorcycle are looking for a real pilot experience, and the loud noise made by the motorcycle is a great quality for this purpose.
The argument could be strengthened if the author explains what kind of driving experience a motorcycle customer is looking for.