It's probably the second sticker you look at (the first being the price sticker).
The new fuel economy and environment labels will take effect with model year 2013 cars and trucks. The EPA is calling the new labels "the most dramatic overhaul to fuel economy labels since the program began more than 30 years ago."
The new labels show more information about fuel economy, such as predicted annual fuel costs (based on $3.70 per gallon), and how much in fuel you would save compared to an average car (an "average" car's mpg is set at 22 mpg). The labels also give a greenhouse gas rating, and a smog rating.
And it wouldn't be an updated label without a way to load it into your smarty-pants phone. Here's a video from the EPA on how that works: