We first provide an empirical sstudy of the energy-saving technological progress on the ENERDATA database. Energy intensity is shown to decrease over the period 1971-1999 in OECD countries, indicating a significant energy-saving technical progress trend. We also show via semiparametric partially linear estimations that : (i) this trend is positively correlated with the investment rate, and (ii) the marginal productivity of investment has accelerated in the sub-period 1985-1999 compared to 1971-1984. Second, we build a general equilibrium vintage capital model with embodied energy-saving technical progress to formalize these findings. In this set-up, we study to which extent a steady increase in the marginal productivity of investment and/or scrapping subsidies could compensate the output loss due to a cut in energy use. The latter fiscal policy is shown to be particularly inefficient in this respect, even under rapid energy-saving technical progress. In the end, our model predicts that the implementation of Kyoto-like protocols in the computers age is much less painful than what it could have been two decades ago.