The White House today released its final rules mandating all new cars and trucks to reach a 54.5-mpg fleet average by 2025.

The rules for updating the Corporate Average Fuel Economy standards -- which each automaker's model lineup is required to meet -- are essentially identical to a 2011 draft issued by the Environnental Protection Agency and the National Highway Traffic Safety Administration.

However, unlike when the Obama administration first proposed increasing CAFE to 62 mpg, a significant number of automakers now support the new standards. The new mandate establishes higher yearly increases starting in 2017 and finishing with 54.5 mpg in 2025. By 2016, automakers have to meet an average of 35.5 mpg.

EPA administrator Lisa Jackson said on a conference call that the new rules “call for steady improvements, not radical overnight changes.” The U.S. would save $1.7 billion in fuel costs and reduce oil consumption by 12 billion barrels through 2025, Jackson said. 

But while gasoline and diesel consumption have been cut considerably -- between 2006 and 2011, fuel stations sold about 35 percent less fuel -- it's unclear if CAFE rules are actually attributable to such massive savings. More so, the U.S. continues to use foreign oil at breakneck pace (since 2000, the U.S. has imported more than 4 billion gallons of crude every year) and while the trends show slight decreases, it's still a large challenge as alternative fuels like ethanol and natural gas remain grounded and fast-charging EV networks are non-existent.

The federal pressure, however, will force automakers to build large pickup trucks that average 33 mpg and full-size cars, with the EPA using the Chrysler 300 as one example, to meet 48 mpg. Such figures all but state the necessity of equipping today's vehicles with electric and hybrid powertrains.

Future 2025 model-year vehicles would save buyers an estimated $8,000 per vehicle in fuel costs over their lifetimes when compared to 2010 models. The EPA did not take into account what the price of fuel would be in 2025, but the White House said the savings are the equivalent of dropping the price of gasoline by $1 per gallon.

However, not all cars are treated the same way. Under CAFE, each automaker has a certain amount of EPA credits to meet regarding its overall fuel economy. Manufacturers can sell excess credits to other manufacturers, or buy credits in lieu of a less efficient fleet. Other automakers, such as Mercedes-Benz, have paid the EPA millions of dollars in fines for not meeting the quotas. While the credit-swapping program remains in place, automakers will gain additional credits for selling electric, plug-in hybrids, natural gas, and fuel cell vehicles. Hybrid pickup trucks are also worth more credits under the new program.

Small automakers like Rolls-Royce that sell less than 5,000 cars per year will be able to petition the EPA directly on a “case-by-case basis” for their own standards. Automakers that sell between 5,000 and 50,000 vehicles are allowed to meet lower fuel efficiency standards but must meet the higher goals in by 2021. Trucks like the Ford F-150 will be allowed more time than cars to meet the higher standards.

According to transportation secretary Ray LaHood, the changes required to make cars more fuel efficient will increase the average cost of new cars by at least $1,800. The new rules are expected to cost as much as $192 billion, according to federal estimates. But the cost savings have some government officials eager to propose mileage taxes -- such as the GPS-tracking measure proposed by California Bay Area cities in July -- to offset declines in fuel tax revenues. In 2009, LaHood suggested a national mileage tax, but the White House shot down that idea almost immediately.