Given the requirements of the modern family, however, consumers are not willing to reduce the size or performance of their vehicles. They have come to rely on these vehicles for the number of people they can carry, their towing capacity, and their unique conveniences.

The ultimate answer may lie in hydrogen fuel cells which appear very attractive. But commercialization of hydrogen powered vehicles is easily 10 to 20 years into the future. We will continue working on this long-term initiative, but I am afraid it is not the answer for today.

Then there are hybrid gas-electric engines, which tend to work best in small vehicles. Unfortunately, it is in larger vehicles -- SUV’s, mini-vans, and pick-ups -- where advances in fuel economy will have the greatest overall impact.

• That brings us to efficient clean diesel vehicles -- that provide excellent performance for both large and small vehicles. This combination of performance and increased fuel economy will substantially lower the Nation’s dependence on foreign oil in the near-term while meeting the demands of consumers.

If diesel accounted for only 30 percent of California’s fleet, estimates are that fuel consumed by motor vehicles in California would be cut in half.

And if diesel could cut fuel use in half nationwide, fuel consumption could be reduced to a level the Nation has not seen since November 1964. These are important fuel economy gains that should not be taken for granted.

• For years the Europeans have enjoyed the fuel economy benefits that diesel engines provide.

More than a third of all vehicles sold in the European Union, and more than 75 percent of all luxury vehicles sold there today, are powered by diesel engines.

But because the United States has more stringent clean air standards than the E.U., it is not simply a matter of importing the existing European product.

We cannot sacrifice current clean air standards for the sake of improved fuel economy. Clean diesel means just that. I will not advocate for diesel engines that do not meet strict U.S. Tier II emission standards.

• Clean, lean-burn diesel is the way of the future for the American consumer. There are, however, some remaining obstacles to realizing this future. Tomorrow I am introducing legislation that will overcome those obstacles and move us toward an efficient clean diesel future.

The bill has four features:

First, it will provide tax incentives for consumers who buy efficient diesel vehicles that produce few emissions.

Many American consumers have bad memories of diesel vehicles from the 1970's. They do not realize the significant advances the industry has made in reducing engine noise and emissions.

When you combine this perception with the reality that clean diesel vehicles will cost more, you have a real problem with consumer acceptance. Consumer tax incentives will offset the increased cost of the vehicle and help to overcome consumer misconceptions.

Second, beginning in January of 2011, it will require that refiners produce and market clean diesel fuel that satisfies requirements for sulfur, lubricity, cetane, and aromatics. These standards are designed to optimize the performance and environmental benefits of these advanced technology vehicles.

Reducing the level of sulfur to less than 10 parts per million will increase the durability and performance of after-treatment technologies used to satisfy U.S. clean air standards.

When sulfur is removed from diesel fuel, however, lubricity may suffer. Replacing sulfur with additional lubricity is necessary to reduce the wear on metallic parts in advanced diesel engines.

Cetane is useful for eliminating cold starts, and it enhances the performance of modern diesel engines.

Lastly, reducing the aromatic content to 15 percent by volume will help reduce air pollution, including particulate matter emissions.

Third, because there will be investment and development costs associated with these fuel specifications, my legislation will also provide tax credits to the refining industry to help offset these costs. And for those refiners that produce clean diesel fuel earlier than the legislation requires, additional tax incentives will be made available.

Fourth, my legislation authorizes the Commerce Department to award grants to cities and states to convert existing manufacturing facilities into clean diesel manufacturing facilities.

Our Nation will not benefit from this, or any other advanced vehicle technology, if we merely shift from a dependence on foreign oil to a dependence on foreign technology and manufacturing. We must ensure that American scientists, American manufacturers and American workers are well-positioned to provide advanced technology vehicles to the world.

This is a plan for the future that can work. Its key principles -- higher fuel economy, lower dependence on foreign oil, and clean air -- are principles we all share. I invite your comments, and ask for your help as the legislation moves forward.