How will U.S. vehicles get 54.5 mpg by 2025?

Last week, the White House announced tougher fuel economy rules that will require automakers’ U.S. lineups of cars and trucks to achieve an average 54.5 miles per gallon by 2025.

Under the plan, President Barack Obama said, Americans will save money on fuel, the U.S. will decrease its dependence on crude oil and tailpipe emissions will be reduced. But it will be up to automakers how they choose to hit the goal.

Of course, there will be more fuel-sipping hybrids and all-electric vehicles in coming years. The addition of even a couple of those high-mileage models could go a long way in helping autmakers boost the overall fuel economy average of their fleets — and still offer big vehicles that are less fuel efficient. However, as a story on points out, there are many ways to skin that cat. Those include a number of small tweaks to vehicles, from boosting performance of small engines with turbo chargers to increased usage of light weight materials, that will be almost imperceptible to consumers.

The proposal essentially doubles the current corporate average fuel economy, or CAFE, standards over the span of 14 years.  U.S. vehicles, under a 2009 plan, were already supposed to achieve 34.1 mpg in 2016. And while a broad group of automakers endorsed the more aggressive rules, some consumer groups note that the costs of hitting the targets will be huge — and American drivers will end up with the bill.