First and foremost, there's the "work truck" classification, which exempts those types of vehicles from these tougher standards. According to John DeCicco, from Environmental Defense, the first CAFE standards from 20 years ago allowed vehicles outside the car category - such as SUVs, light trucks and minivans - to survive with terrible fuel economy. Now the story could be repeated with larger vehicles that technically fit the definition of "work truck" but probably aren't used for work (the article uses the 2008 Ford F-250 Super Duty with King Ranch trim as an example) to again skate by legislation.
Then there's the issue of weight reduction, which has actually been a way to go for several car manufacturers (we even have a full category for it) to increase mileage ratings. But could this lead to cars that are less safe? The truth is that fuel economy targets will vary according to a vehicle's attributes - most likely size, measured by "footprint" or the area bounded by the four wheels, which is a system that ensures that automakers won't sell a bunch of smaller cars together with larger less efficient vehicles. However, this could also lead to cars that would weigh less than similar counterparts from the late '90s or early 2000s, which are, according to DeCicco, simply overweight.
The "footprint" of the car could also lead automakers to push wheels against the corners of the cars, something that might affect Honda or Nissan, marques that already sell smaller vehicles, says Ed Cohen, chief Washington lobbyist for Honda North America Inc. He also believes that some automakers will simply cope with the cost of fines (or add it to the price of the car), something premium marques have been doing in the past. Jim Kliesch, an engineer in the clean-vehicles program of the Union of Concerned Scientists, says: "It's going to be a fairly simple process," and he forecasts that this will only cost about $1,500 per car.