Sooner or later 35 mpg (6.7 L/100 km) for cars and trucks, or maybe 35 mpg for cars and 30 mpg (7.8 L/100 km) for trucks, is going to be the law of the land. One proposal in Washington would require 35 mpg for all vehicles by 2018.

That’s still a ways out. I figure it will happen about the time the Detroit Lions make the playoffs. Today, 35 mpg for cars is not that difficult. For trucks there's a problem, even at 30 mpg. Let me explain. For cars, going to 35 mpg from today's corporate average fuel economy standard of 27.5 mpg (8.5 L/100 km) is a 25% increase.

Getting there requires technology: lightweight materials, E85 ethanol and fuel-saving transmissions. Chrysler is going to the double clutch as standard, and 6-speed automatics are common. Next come 7-speeds. That 25% gain is practically within grasp.

Make cylinder deactivation universal for all V-8s, and try it on V-6s. Chrysler says it will improve fuel economy more than 6% by using cylinder cutoff on V-6s. And let’s standardize stop-start systems to shut off the engine at red lights and at idle.

Stay on the diesel and hybrid track. It's reasonable to expect Detroit eventually will build a Toyota Prius-like hybrid that gets 45 mpg (5.2 L/100 km) and sell a flock of them. The plug-in hybrids that GM keeps talking about might actually work.

Do the numbers: These changes bring you within striking distance of 35 mpg. Trucks are another story. Going from 22 mpg (10.6 L/100 km) to 35 mpg is a 50% increase – very tough to do.

Yes, we see hybrids coming this fall in big SUVs at GM and Chrysler. They and Ford all promise to have diesel light pickups by 2010, which could mean a 25% fuel economy increase. With the added cost of a diesel (up to $5,000), we don't know how many buyers will take them.

These are big, heavy vehicles, and putting them on a weight-reduction plan could run up costs big time. But it can be done, if our government and auto makers get creative.

For instance, perhaps the new CAFE rules will not apply to trucks used for work. A local official would certify that a pickup, SUV or minivan is a work vehicle, meaning you hand him $200 for a special stamp. Sort of like those handicapped parking tags we often find in cars owned by the able bodied.

For non-commercial pickups, we have the “drafting credit.” They get a 3-mpg (1.2-km/L) credit because cars get behind them and “draft,” or are pulled along by the vacuum, saving fuel.

Yes, trucks are tough, but one way or another, we'll manage. I was a Washington bureau chief for a few years and learned the way the system works. Our legislators wouldn't want to make Toyota or Nissan shut their new U.S. truck plants.

The message to Detroit: Where there's a will, there's a way.

Jerry Flint is a columnist for, and former senior editor of, Forbes magazine.