Will Tighter CAFE Rules Bring More Trucks, Fewer Small Cars?

The entire auto industry was startled when Fiat Chrysler said two weeks ago it would end production of its Dodge Dart compact car and its Chrysler 200 mid-size sedan.

The company intends to use the plant capacity freed up to build more light trucks, meaning its popular crossover utilities and pickup trucks.

Coverage of the news immediately questioned how Chrysler would be able to meet increasingly high fuel-economy requirements from now through 2025.

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But an article in last Saturday's Detroit Free Press hints at a different way to arrange the puzzle pieces.

What if Chrysler has a better chance of meeting Corporate Average Fuel Economy standards precisely by dumping passenger cars and focusing on trucks?

Here's the reasoning.

While the 54.5-mpg fuel-economy average for 2025 got all the headlines in 2012, the regulations are far more complex than a single efficiency number that every vehicle must meet.

(For the record, that "54.5 miles per gallon" also translates to around 40 mpg on the EPA-adjusted fuel-economy part of any new vehicle's window sticker.)

The regulations are graded by "footprint," and smaller passenger cars have a more aggressive ramp (5 percent a year) than larger light trucks (at 3 percent a year).

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Based on its specific mix of sales, every carmaker has fuel-economy numbers for each of many different categories of vehicles, adding up to a unique target for that maker.

But the basic rule is that trucks must increase their efficiency less aggressively than cars.

So a maker that sells mostly cars--take Volkswagen, for example--has to increase the efficiency of its lineup much more, proportionally, than a truck-heavy maker like FCA.