I would imagine that any loss in fuel economy after getting an intake is due to the driver enjoying his new toy

However, I can testify that I got 40mpg w/ my short ram intake (really a dirty K&N cone filter and an adapter) when I was driving to Florida this past summer, averaging 78mph w/ an auto. I also usually get an average of 27mpg around town w/ my intake. This is in a nearly 10 year old car w/ an auto tranny.