You are right that I neglected to analyze the degree of warning carefully. My view is that, as long as the current lack of transparency into reserves holds, there won't be lots of warning. People only pay any attention to peak oil (and resource constraints in general) when prices are high (as in the 70s, which concern dissipated through the 80s and 90s, and now). Current prices are pretty much constrained to be not much lower than the future prices (via storage arbitrage). Historically, future markets have had extremely limited ability to correctly predict future oil prices (unsurprising given the lack of transparency into most sources of supply). Not only that, it's human nature to only respond to things after they've happened (no-one took very seriously that terrorists could fly planes into buildings or that New Orleans could flood until after those things had happened). If we are near peak now, we are starting to respond. If it turns out we are not, and there's some big new supply somewhere, we'll all go back to sleep until we are near peak (as we did in the 80s/90s).

Overall, I sort of assumed the warning of the decline rate is enough to set in place those 2x improvements in transportation efficiency, but not more. If we were to start constant decline next year, we obviously would not achieve 2x for some years because manufacturors would need to design new models (except Toyota and Honda), and rejig factories (in all cases).