[ars]

But caused a significantly greater demand for energy to make new cars.

If it was worth it to trade your guzzler for a new car people would do it on their own without incentives. But a new car uses more energy than it saves for many many years. It's only worth it when the old car dies.

[cellularmitosis]

I have a hard time believing this. Let's take an environmentally attractive car, like the TDi Jetta. How many barrel-of-oil equivalents would you estimate it takes to produce a car like this, in mass quantity?

[ars]

About 200 to 300 barrel of oil. Or about 20 - depending on who you ask.

Basically how far down and across the manufacturing chain do you count the energy. Most places use the second number since it's direct energy for that car. I prefer the first since it also includes things like overhead for the sales team, the engineering, building the manufacturing plant and everything else it takes to actually make a car.

[cellularmitosis]

Whoa. For reference, 300 barrels of at today's prices is over $24k.