Automakers and their suppliers are racing to develop technologies to meet strict new CAFE standards.
The rules will require companies to reach a fleet average of 35 miles per gallon, roughly, by 2017, and an eye-popping 54.5 (roughly) miles per gallon, by 2025.
But despite all the stories you've heard about electric cars powered by advanced lithium-ion batteries, chances are, you won't be owning one by 2017 - and probably not by 2025, either.
Electric cars will be just too impractical and expensive for most people in the near future.
Not your grandfather's ICE
Instead, if you buy a new car in the next five years, it's more likely to be powered by that old standby - the internal combustion engine (ICE).
But it will be a vastly more fuel-efficient engine. And everything else in the car, from the batteries to the tires, will be tweaked to squeeze out a little more fuel efficiency.
True, by 2025, many more cars will be hybrids - but they will still use internal combustion engines. There could also be many more natural gas-powered cars - but those, too rely on ICE. It's just the fuel that's being combusted inside the engine that's different.
Most car companies will downsize the engine to reduce fuel use (on Monday, Ford Motor Company is expected to announce which car will boast its new three-cylinder engine) combined with turbo-charging to preserve the performance that Americans expect from their cars.
Turbo-charging involves injecting air and fuel to boost an engine's performance when it's taking off from a dead stop, or accelerating quickly.
But turbo-charging an engine can create a new problem - turbo lag. That's the perceptible delay before the turbo-charging kicks in. And the last thing car companies want is for Americans to feel the performance of their cars has worsened in response to CAFE.
Auto suppliers say they can help.
New technologies to help the old technologies work better
Global auto supplier Valeo, for example, has developed a device called a "supercharger" to prevent turbo lag.
The company says the device can also boost fuel efficiency by 17%.
"It enables to do further downsizing of the engine," says Pierre Emmanuel Strohl, the company's Product Marketing Director, "and also what we call down-speeding of the transmission, so you run always on low rpm on the engine."
And importantly, Strohl says the device is relatively inexpensive.
Cost will be tremendously important to car companies. The fear is cars could become unaffordable in the process of meeting CAFE.
Older technologies get better, too
While Valeo's device is new, existing technologies are also being improved to boost fuel efficiency.
Exide Technologies is investing in advances in lead acid batteries - the kind of batteries in our cars today.
Paul Gumber is Exide's Director of Engineering for Automotive OEM.
"It's an old technology," says Gumber, "but that's the advantage of it. It's very proven, and it's very well known."
And it's cheaper, much cheaper, than the new kid on the block, aka, lithium-ion batteries, the kind powering most electric cars.
Exide figures as more and more auto companies adopt "stop-start" technology, they'll need better lead acid batteries to deal with the heavier demands on the battery.
Stop-start technology allows the car to automatically turn off when the car comes to a stop, as at an intersection, then turn back on when the driver hits the gas.
Exide recently partnered with Maxwell to offer an advanced lead acid battery that works in conjunction with a ultracapaciter, which is a different kind of energy storage device.
Will we make it? Maybe - maybe not
Every other link in the supply chain -- tires, steel, steering, brakes, and on and on - is focused on helping automakers achieve the CAFE goals - which Pierre-Emmanuel Strohl calls a "big stretch."
That's in large part because Americans drive bigger, heavier cars than people in other parts of the world.
And if too few are convinced to buy a smaller car, with a smaller engine -- and almost certainly, a bigger sticker price -- 54.5 mpg could remain an unreachable goal.