Automakers have long known there's a double standard for gas mileage.

Cars have to meet higher goals, trucks have less stringent requirements. And the larger the vehicle, the lower the average fuel economy it has to deliver.

The proposed fuel economy standards for 2017 through 2025 vehicles perpetuate those distinctions.

Worse, the new rules continue profit incentives that led car companies to reclassify hundreds of thousands of vehicles not as cars but as light trucks--meaning their required gas mileage was lower.

And the standards may encourage automakers to enlarge vehicle footprints, lowering the mileage they must deliver.

The proposed standards issued jointly by the EPA and NHTSA require a corporate average fuel economy (CAFE) level of 54.5 mpg by 2025.

That translates to EPA gas-mileage ratings in the low to mid 40s (lower than today's 2012 Toyota Prius and 2012 Toyota Prius C hybrids)--perhaps as little as 35 mpg in the real world, according to the Union of Concerned Scientists.

Truck = "non-passenger vehicle"

First, the car vs. truck rule. That distinction made sense in the 1970s, when sport-utility vehicles and crossovers didn't exist (back then, they were station wagons) and the idea of using a crude, uncomfortable, utilitarian pickup truck as personal transport was an oddity for most drivers.

That changed in the 1990s, and the importance of the distinction came to public light in late 2004, when Subaru actually changed its all-wheel drive Outback sedan to a "light truck" from a car simply by jacking up the ground clearance.

Every Subaru sold in the U.S. is fitted with all-wheel drive--so it merely had to raise the ride height of its Legacy sedan to truck levels and, voila, instant "non-commercial vehicle," and instantly lower MPG requirement.

(As it turned out, few buyers wanted a jacked-up sedan with side cladding and graphics; Subaru dropped its Outback sedan for 2010. But it did the same to Outback wagons as well, which became trucks for 2005 and have stayed that way.)

AWD for family haulers

But in fact, AWD and ride height are two of the criteria used to distinguish between a "car" and a "light truck" under CAFE rules.

2003 Ford F-350 Power Stroke

2003 Ford F-350 Power Stroke

Other criteria include the shape of the load bay, and the presence of folding or removable seats. If a vehicle meets most of these criteria, it can be designated a light truck--as many minivans and crossovers are today.

Don Anair, a senior engineer in the clean vehicles program of the Union of Concerned Scientists, writes today on the UCS blog about why the difference between cars and trucks matters for fuel economy.

The UCS had previously written about the "loopholes and weak standards" for pickup trucks and large sport utilities in the new standards, which it generally lauded.

Does your crossover carry people?

Anair notes that the vast majority of all-wheel drive crossovers and sport utilities, defined as "non-passenger vehicles," are not used in commercial, agricultural, or industrial use, but solely for personal transport.

In fact, AWD has become a safety feature for family haulers, even though it will never be used off-road or even on anything muddier than a school soccer field. In regions with snowy and icy conditions, it is a must-have feature for many classes of vehicles.

2012 Honda CR-V - First Drive

2012 Honda CR-V - First Drive

According to EPA gas-mileage ratings, adding all-wheel drive to a 2012 Honda CR-V reduces mileage by roughly 3 percent. But the new standards allow a 16-percent difference, meaning that Honda has an incentive to sell more of its CR-Vs as "light trucks" rather than cars.

Anair proposes that it's time to revisit the definition of a "truck," and he will be testifying to that effect today at a public hearing on the proposed rules being held in San Francisco.

Footprint formula for safety

Second, the footprint formula. U.S. gas-mileage rules were changed in 2006 from a pair of standards--one for cars, one for trucks--to a "footprint based" formula, in which different vehicle sizes were assigned different fuel efficiency targets.

That reduced the chance that all cars would get smaller, and hence (theoretically) less safe.

Perhaps not coincidentally, it also protected full-line domestic automakers--which at that point were arguably unable to make money building compact and subcompact cars--by ensuring continued sales of profitable trucks.

2012 Chevrolet Sonic hatchback, road test, Catskill Mountains, Oct 2011

2012 Chevrolet Sonic hatchback, road test, Catskill Mountains, Oct 2011

For a more detailed explanations of the "tall grass of CAFE’s sordid, politically charged history" and the undeniable complexities of auto design tradeoffs, Popular Mechanics has a nice summary.

But it created a perverse incentive: Build a car with the interior space of a compact, but on a mid-size footprint (to kick it into the larger vehicle class), and it would only have to meet the lower mileage standard of the larger car. Meaning compacts that are ... errr ... more compact get penalized.

"Substantial incentive" for larger vehicles

A University of Michigan study published in Energy Policy noted, "there may be a substantial incentive to produce larger vehicles" that could "undermine the goals of the policy."

The U of M researchers created a simulation that allowed modeling of supply and demand, engineering tradeoffs, and other variables to ascertain likely vehicle mix in future years under the new standards.

The study team concluded the goal of preventing smaller cars "overshot its target," and in fact created incentives for automakers to build larger and more truck-like vehicles.

But, said Kate Whitefoot, who conducted the research and is now a senior program officer at the National Academy of Engineering, "the policy can be adjusted to reduce these unintended incentives."

2005 Subaru Outback Rear

2005 Subaru Outback Rear

So ...

It's important to point out that the new regulations will still enormously increase average fuel efficiency and reduce U.S. gasoline consumption--which peaked in 2006 and has been falling since.

Nonetheless, the rules appear to create perverse incentives to make vehicles larger, heavier, and less efficient.

What can be done?

Well, the comment period on the proposed 2017-2025 regulations is still open. You can submit your thoughts from now until February 13.

Clean-car and fuel-efficiency advocates--and, we hope, the energy security folks with whom those groups don't always see eye-to-eye--will surely also weigh in on the rules.

But, tell us: Does airing these concerns run the risk of making "the perfect the enemy of the good"?

Leave us your thoughts in the Comments below.


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