Do you know what it feels like to drive a car that gets 150 miles per gallon? It feels like the future has arrived.

I know because last month I tooled around Capitol Hill in a Toyota Prius, modified to be a plug-in hybrid electric vehicle (PHEV) with an A123 Systems lithium-ion battery.  A conversion kit will be available to drivers before the end of this year to turn a standard gas-electric hybrid into a plug-in hybrid.

The ramifications of the arrival of the plug-in hybrid for national security and the environment are profound, but the concept is simple. Plug your car into a 120-volt outlet at night and drive it the next day for up to 40 miles off that charge. For longer trips, the battery will recharge while you drive, using gasoline or even environmentally friendly biofuel.

This leap-frog technology is on the cusp of commercialization. General Motors also is planning for the introduction of a plug-in hybrid, the Chevrolet Volt, in several years. America is leading in this technology and we have an opportunity to revitalize our domestic auto industry. We should take it.

Plug-in hybrids dramatically will reduce both our dependence on foreign oil and our greenhouse-gas emissions. For these reasons, Congress and the Bush Administration should make it a focus when considering policies aimed at immediately addressing two of our most pressing problems: national security and global warming.

In contrast, many proposals on the table involving transportation don’t solve both of these problems at once.  Some so-called alternative fuels, like liquid fuels from coal and tar sands, may wean our addiction to foreign oil, but provide no environmental benefit.

To prevent what scientists predict are worst-case climate change scenarios, we need to reduce U.S. greenhouse-gas emissions by 80 percent below 1990 levels, by 2050. This will require an aggressive American cap-and-trade system to limit carbon-dioxide emissions from power plants and industry. But it also will require dramatic reductions in carbon-dioxide emissions from the transportation sector, which accounts for roughly one-third of our nation’s total greenhouse-gas emissions.

For the transportation sector, fueling plug-in hybrids with electricity and biofuels offers the most net benefits of alternative fuels compared to gasoline. Take a look at the numbers.

The Environmental Protection Agency (EPA) recently completed a study of alternative transportation fuels — which accounted both for energy density and the lifecycle carbon emissions of the fuel — and compared all results with regular gasoline. They concluded that the net reduction in greenhouse-gas emissions from replacing gasoline with ethanol made from corn is 20 percent.

Electric fuel used by plug-in hybrids leads to a 45 percent reduction over gas, even accounting for the fact that coal-fired power plants currently produce over 50 percent of the U.S. electric energy mix, because electric engines are roughly 65 percent more efficient than traditional combustion engines. The vast improvement of electric fuel over gasoline will only increase as utilities move to clean sources of energy, like wave, tidal, solar and wind power.

Even better, new biofuels can be used in plug-in hybrids to further decrease emissions. Currently, cellulosic ethanol holds the most promise, as it produces 90 percent less carbon dioxide than regular gasoline. What other technology will get cleaner over time?

We have the added possibility of using coal to power transportation, by burning it cleanly, sequestering carbon dioxide and transmitting its electricity into our plug-in hybrids. This would combine American coal with American technology to drive our cars.

But the alternative, converting coal to liquid fuel for cars, leads to an astonishing 118 percent increase in greenhouse-gas emissions over gasoline, according to the same EPA analysis of transportation fuels. This is because the production of liquid fuel from coal is very energy intensive and carbon-emitting fossil fuels typically drive this process.  Even if these production processes use carbon capture and storage technology, the net result is a liquid fuel that generates just as many greenhouse-gas tailpipe emissions as regular gasoline.

The lesson here is that it makes more sense to run vehicles on electricity, even when coal is a significant part of the energy mix, than it does using coal to liquids. Plug-in hybrids also allow for better fuel diversification, as they rely on grid electricity from a range of sources and are compatible with gasoline, ethanol or other biofuels. This will prevent spikes in transportation fuel costs due to seasonal changes or regional problems.

As Congress moves forward on global-warming legislation, we should include in any comprehensive policy provisions to promote plug-in hybrids, like my Get Real Incentives to Drive (GRID) Plug-in Act, H.R. 589. If we enact such a measure, cars that get 150 miles a gallon won’t just be showcased on Capitol Hill. They’ll roam American streets and recharge in our garages. Best of all, they’ll be a sure sign that we’re on the road to our clean-energy future.

Inslee is a member of the House Energy and Commerce Committee and Select Committee on Global Warming.