For the last few months as the future of the US auto industry has been debated, the idea that Detroit would be in fine shape had they simply been producing greener cars seems to be taken by most of the media as gospel truth. But with US and foreign automakers’ sales lagging far behind ‘07 numbers, it hardly seems sales of gas sippers are beating the gas guzzlers. So, the green car refrain fails to take into account the overall demand trends or the changes Detroit and its suppliers must make to survive.

As HuffingtonPost reported yesterday, December auto sales were down 32% for Ford, 31% at GM and 53% for Chrysler. But Honda - America’s self proclaimed greenest car company - also saw sales drop 35%, while Toyota, fell 37%. In fact even the pinnacle of green cars, the Prius plunged a whopping 45%, outpacing the overall US auto sales decline of 36%. The forecast for Prius is so soft, Toyota has delayed opening a new Mississippi plant for the popular hybrid.

On the consumers’ side of the equation, growing unemployment, declining consumer confidence, a shockingly high gas price peak in 2008 and a tight credit market have combined to crush consumer demand. Like all economic cycles, this too will pass. Certainly updating their product lines to reflect volatile oil prices, longer commutes and global (rather than only US) demand trends, would help prepare Detroit for the rebound.

Now don’t get me wrong, I think more efficient cars would have been a better direction for sales, competition on the global stage (just look at Ford’s long record of success abroad with the Focus), the environment and reducing oil demand/dependence. But moving in that direction now won’t clear things up overnight.

In the mean time, US and foreign car makers must get through the current economic crisis. And since they share many of the same suppliers, the automakers are all in it together. So, what do they do if simply going green won’t cut it? My colleague Dan Kowal gave his strategy advice recently. Dan’s recommendations included strategic sourcing, a halt to supplier price increases, innovation and collaboration. Seems to me those concrete steps are a far better strategy for survival than hindsight criticism and the promise of the green cars would cure all panacea.

Justin Fogarty is Managing Editor of Supply Excellence. For any questions or feedback on the blog or its contributors, Justin can be reached at jfogarty[at]ariba.com.