It's not like it was a surprise, and yet the magnitude of it still managed to astonish me somewhat. Yes, I'm talking about the abysmal March car sales automakers reported Tuesday. Wait, wasn't it April's Fool's? Was it just a hoax? I wish, but this was no joke, only another sign of the condition of the U.S. economy. Consumers, burdened by record high gasoline prices, a housing correction not seen in many years, a credit crunch and food inflation, decided big ticket items should not be on their shopping list.

In numbers, General Motors Corp. (NYSE: GM) reported a 19% drop in U.S. sales during March, Ford Motor Co. (NYSE: F) reported a 14% decline, Chrysler - a 19% decrease, and even Toyota Motor Co. (NYSE: TM) said sales were down 10% compared with a year ago sales. Nissan Motor Co. Ltd. (NASDAQ: NSANY) sales fell 4% and Honda Motor Co. (NYSE: HMC)'s 3%. Porsche -- much like Ford's recently sold luxury brands -- had a bad month with a 25% drop in sales, while BMW 's sales were down 5.4%.

Now, automakers warned things could get even worse in the near term, which should make investors worried, especially those holding shares of Ford and GM. The already struggling American companies, already losing money in North America, stand to feel the revenue loss, and being in the midst of massive restructuring, that could hurt their ability to weather the storm.

In addition, while Toyota this time joined GM and Ford in sales declines, Japanese car makers still seemed to fare better in this climate of higher fuel costs and the smaller disposable income of consumers. Indeed, Honda and Nissan actually posted car sales gains of 3% and 10% respectively, which were eroded by decreases in truck sales. With Japanese and South Korean carmakers making smaller and more fuel-efficient cars, their market share in the U.S. keeps increasing, as it did in March too by 2.6 points to 44.5%. How can it not with Toyota's subcompact Yaris sales rising 83% and Honda's subcompact Fit surging 74%?

Even within the Big 3, car sales fell less than SUV and truck sales that were also hurt by the slowdown in the housing market as there was less construction. Sales of Ford F-Series pickup were down 24%, while Ford focus sales were up 24%.

Ford and GM needed to answer to changing market conditions years ago, given the nature of the industry. They misread the market and haven't reacted in time. Investors can only hope it is not too late.