In the end the point is that energy is not properly priced, but in many cases subsidized. And in the case of nonrenewable energy sources, the cost of depletion is something that can hardly even be estimated. Just because a cost cannot be estimated doesn't mean it's not zero.

A society committed to the notion that government is always bad will have bad government. And it doesn't have to be that way. — Paul Krugman

I'm not sure about the congestion point. There has not been a railroad system that supported anything like the volume of travel that is currently supported by the automobile.

Really? I think that you didn't read the linked resources carefully enough. Between 1964 and 1976, the Shinkansen managed about a hundred million passengers a year. By 2004, the segment of the Shinkansen between Tokyo and Osaka has carried 4.16 billion passengers. This is for long-distance inter-city transport, remember, so we're not competing with all car use, merely a subset of it combined with inter-city busses and continental airline flights. Intra-city transport is better accomplished by metros, light rail, or even bus networks.

I think one must be careful about the train versus car efficiency argument. Trains, for example, are big. You get a dining car, aisles to walk around in, lots of extra space that you don't get in a car--and that needs to be carried around with the people.

No, actually, you don't need any of the above. And in fact, hauling that stuff around is still plenty efficient. Remember, cars are subject to a massive inefficiency because they have to haul their fuel around with them. Trains don't have this problem, which gives them a lot of wiggle room, especially on long journeys.

Also, the fixed A-to-B routing with intermediate stops means that at the ends of the run the train may be mostly empty--something every tram or train commuter is familiar with. And it's true that steel wheels on steel rails have very low friction, but low rolling resistance car tires have low friction--and it's a space that has not been fully explored by the technologists.

Most of the passengers on most trains for a fixed, long-distance A-to-B route will be travelling between A and B. Moot point. The friction is also a moot point - even if the car's wheels can achieve the same efficiency as rail wheels, it'll still be worse than a maglev, and the car will still have to haul its fuel around with it. You can't just wave the magical technologist wand and say "cars will be better".

But again, the point is that perhaps trains ARE more energy-efficient than cars, but even so, if people are willing to pay more to have the flexibility of the car, it is worthwhile to allow that--if in both cases they meet the broad social objectives.

They don't. Cars rely on oil. Oil is limited in quantity. Oil is really dirty. We need - and have - a reliable alternative.

I think one must be careful about the train versus car efficiency argument. Trains, for example, are big. You get a dining car, aisles to walk around in, lots of extra space that you don't get in a car--and that needs to be carried around with the people.

Let me turn this into a point that actually carries weight (because, carrying empty space, cost nothing). Indeed it is true that while on a modern train with average filling (40-50%), you have roughly 1 ton for 1 passenger, while for a car (a car not a SUV), you have that when just the driver sits in it.

However, mass is the main factor only when you accelerate. At constant speed, friction is the factor, and trains rule. But even acceleration doesn't really make them worse. On one hand, trains typically gain speed/brake with much lower accelerations (no 100 km/h in ten seconds). On the other hand, modern electric trains (especially those using a lower-than-grid-frequency separate railway AC system, say the 16.7 Hz in Germanic and Scandinavian countries) have regenerative electric brakes, and send much of the braking energy back to the catenary - which can have a greater efficiency than even hybrid cars that recharge themselves while braking. (There are also experiments with adding gyros to diesels for similar short-term energy conservation.)

_{*Lunatic*, n.
One whose delusions are out of fashion.}

I hear the arguments pro and con, but still we are missing the point, which is that the anti-car sentiment must be separated from the anti-CO2 emissions argument.

• Cars need not carry their fuel with them, as already discussed. Even if they do, battery technology improves constantly. According to this article batteries on the brink of commercial availability are five times better than the best ones available right now. That translates into about a 500 mile range for a GM EV-1 car.
  
• "Think about the way you drive" doesn't prove anything, because we shouldn't be talking about future perfect trains compared to today's cars. If slow acceleration is important--and as a hybrid driver I assure you that it is, because of hysterisis loss in the rubber of the tires--then change the way cars accelerate. That's why the 2CV can pass me in the morning.
  
• No particularly good statistic about long distance car travel leaps immediately to mind, but the seven lane Tappan Zee bridge in New York, on a route perhaps comparable to the sort that a high speed interstate railroad might take, carries 135,000 cars per day. If there are perhaps 1.2 people per car average, that's about 60 million passengers per year--a favorable comparison to a train running in Japan's heaviest traffic corridor.
  
• Also, I don't see what's wrong with waving a technological wand around. Is there some problem with thinking that technology--of both cars and trains--will change in years to come?

Jerome is correct in saying that one of the big problems is the subsidy of oil. One might work on that problem and then find out whether cars are still undesireable. In the meantime, nobody can prove which will be better in the long run, so making a political pro-train decision based on rough comparisons of today's technology is not going to give the best answer.

Incidently, here is a pretty long list of American cities where the use of mass transit has increased recently: http://www.apta.com/media/releases/050926gas_prices.cfm