Falling gas prices has been great news for just about everyone except Toyota: Prius sales are taking a hit.

Toyota had previously expected to sell a quarter million of the hybrids in various formats in 2013, perhaps asking too much against a decline in gasoline prices. Leave it to Americans to stop buying fuel efficient cars when gas prices decline. Toyota recognized that gas prices could be a culprit, telling various sources that gasoline gas prices may endanger the goal.

"It'll be a challenge," Lentz said of meeting the goal in an interview with Bloomberg. "We'll continue to push Prius and Prius family, but if it ends up that demand is less than the sales forecast, that may be adjusted."

As vehicle sales numbers have previously shown, Americans turn to less fuel efficient vehicles when gasoline prices decline. Such was the case with the crash in gas prices in 2008/2009 when sales of pickups and trucks increased, helping beleaguered car manufacturers.

And while sales numbers of Priuses may not meet the perhaps lofty goals, keep in mind that Toyota still sold an average of 236,000 of them in the United States in 2012 under four different models.

Do fuel prices have a great impact on what you look for in a car or how fuel efficient it is? Sound off in the comments.