In the latest draft of new fuel economy and emissions standards obtained by the Associated Press, the Trump administration argues that reducing mileage standards will improve safety.
It's an argument that dates back to the beginning of fuel economy standards in the 1970s, and one that ignores technological improvements made along the way.
Under the Trump administration, the EPA, which governs tailpipe emissions standards and conducts fuel economy testing, and the NHTSA, which has authority over corresponding fuel economy standards, have been threatening to roll back increases in those standards implemented under the Obama administration.
Sources have said the final proposal could be released as early as this week.
An earlier draft, released in April, proposed to freeze the fuel economy increases at 2020 levels through 2026.
The new draft obtained by the AP, and published by KPIX, the CBS affiliate in San Francisco, argues that freezing the standards could save 1,000 lives per year.
The argument is two-fold. First, the draft says that reducing mileage standards would limit weight reductions for new cars, and that heavier cars are safer. It argues that the Obama administration, when it proposed the fuel-economy increases, underestimated the weight reductions that would be necessary to achieve the standards. This weight equals safety argument is what gave safety regulator NHTSA authority over fuel economy standards rather than the EPA or another agency.
Second, it claims that improving cars' fuel economy would cause Americans to drive more, increasing the risk of crashes.
Both arguments date back decades but ignore data that shows that highway deaths have been reduced dramatically, even as miles traveled have increased and cars have gotten more fuel-efficient.
David Zuby, the chief research officer at the insurance industry-funded IIHS, told the AP, "They're making assumptions about stuff that may or may not be the same." He cites the wider adoption of automatic emergency braking as one factor that could reduce deaths to offset weight reductions, for example.
All other things being equal, basic physics dictates that a heavier car will fare better in a crash with a smaller one. With the race to new technology, however, all other things are rarely equal. Electric cars, for example, rely on heavy battery packs that often increase the vehicles' weight compared with gas engines, yet have the highest EPA fuel-economy-equivalent ratings of any cars tested.
The IIHS famously conducted a test where it crashed a 2009 Chevy Malibu head on into a 1959 Chevy Bel Air to show how much better occupants of the smaller modern car fared compared with the old car.
The argument that higher fuel economy causes people to drive more has been studied extensively. The trends toward more efficient cars corresponds with the growth of suburban sprawl, but any causal link has been tenuous.
When the EPA released a first draft of its proposal to limit mileage standards back in April, 16 states promptly sued the agency, so any actual change in fuel economy or emissions standards is likely to be tied up in courts for years.
Insiders have been expecting the Trump administration to release the new proposal any day in the past couple of weeks, but the AP report says that details are still being ironed out. We will report on the proposal as soon as it is released.