Columnist: Many car manufacturers trumpet their cars' fuel economy under normal driving conditions. For all three of the cars I have owned, I have been unable to get even close to the fuel economy that manufacturers advertise for cars of those makes. So manufacturers probably inflate those numbers. The reasoning in the columnist's argument is most vulnerable to criticism on the grounds that the argument ['uses the term "fuel economy" in two different senses', 'draws a conclusion on the basis of a sample that is too small', 'presumes, without providing justification, that driving conditions are the same in every geographical region', 'presumes, without providing justification, that car manufacturers knowingly market cars that fail to meet minimum fuel efficiency standards']