The May U.S. sales numbers for the auto industry were released yesterday, and they were impressive nearly across the board. The automakers combined to post the strongest month of sales since August, reporting a jump of 7.4%. This is particularly astounding considering the continuing increase in fuel costs.

Despite record-breaking gas prices, SUV and truck sales were surprisingly strong. In fact, General Motors (NYSE:GM) reported an 11% increase in truck sales, while car sales actually decreased by 0.4%. Overall, the top automaker reported an increase of 6.5%.

GM's primary domestic competitor was the only major player to report negative results for the month. Ford (NYSE:F) generated a disappointing 3.1% decrease in domestic sales, with a drop in sales of both cars and trucks. The consensus seems to be that Ford needs to revamp its aging lineup. The company continues to roll out the same bland designs year after year. However, the release of its new hybrid SUV should help improve its image somewhat.

Even the long-suffering No. 3 U.S. automaker picked things up in May. DaimlerChrysler (NYSE:DCX) reported a 5% increase in sales for the month.

Contrary to the mixed results reported by the top American automakers, the top Japanese manufacturers continue to shine the brightest. Less than a month after reporting its record-setting year, Toyota (NYSE:TM) recorded its best month ever in its 47 years in the U.S. market. The company reported an increase of 12.6% for the month, selling a record 202,420 vehicles.

The two other big names in Japanese autos, Honda (NYSE:HMC) and Nissan (NASDAQ:NSANY), also reported remarkable sales. Like Toyota, Honda, which was partially boosted by its Acura division, had a record month in May. The company increased its sales by 14% to 143,193 for the month. The smaller, yet fun and reliable, Nissan brand saw its sales jump by an unbelievable 28.4%.

While domestic and foreign auto sales were impressive overall, the American manufacturers have to be concerned about the pace their Japanese competitors are setting. It's no secret that the Japanese manufacturers are better known for their reliability, value, and performance. Now, the U.S. automakers are even lagging in hybrid technologies. If the Big Three hope to remain competitive, they may want to follow their foreign competitors' lead and start producing a broader range of products that consumers want.

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Fool contributor Mike Cianciolo welcomes feedback and doesn't own any of the companies in this article.