From another website:

"In a paper received by Toyota Motor Corporation it reads, "Manufacturers are required by law to use the EPA-estimated fuel economy ratings on every Monroney label (window sticker), and must state those ratings in advertising that quotes fuel economy figures. According to Chris Rundler, Director of EPA and Dan Harrison, Manager of EPA cars, this is not the case. "A Manufacturer can voluntarily use MPG labels of their own if the figures they have are lower." The operative words in this case are "if the figures are lower." "