Auto assembly plants escaped the brunt of the devastating Japanese earthquake, but supplies of hybrid cars and other fuel-efficient vehicles in the United States will be affected—as Japan comes to terms with damaged roads and infrastructure. Major Japanese automakers have plants in the United States to produce popular models that sell here, but the best-selling hybrids are manufactured in Japan.

The timing for a disruption of distribution of hybrids comes at a time when high gas prices have produced greater demand for gas-electric cars and other small fuel-efficient vehicles.

Earl Stewart, of Earl Stewart Toyota in North Palm Beach, Fla., told the New York Times: “The timing could not be worse. I don’t know how long it will take to get the roads and ports cleaned up and get Priuses back on the ships.” He said that he put used Priuses on his showroom floor because the dealership doesn’t have any new ones. Toyota Motor Corp. has not released an official statement about Prius supply.

As we reported last week, dealer discounts for Toyota Prius and other hybrids have vanished with high gas prices and the resulting higher demand. The impact of the earthquake could mean even fewer deals on hybrids.

Honda dealers in the United States get more than 80 percent of their cars and trucks from North American plants—but hybrid models such as the Honda Insight and Honda CR-Z are made in Japan. Honda officials said the company couldn’t get products out of Japan due to damaged roads.

Toyota produces its Toyota Camry Hybrid, the fourth best-selling hybrid in the United States last year, in Kentucky. During the last run of high gas prices and hybrid demand in mid-2008, Toyota made plans to build the Prius at a new plant in Mississippi. The company canceled those plans in late 2008 during the economic downturn.

Nissan is also grappling with the effects of the earthquake—as the company works to fill orders for the all-electric Nissan LEAF. “We’re still assessing the situation and yes our manufacturing facilities are closed through Monday at this point,” said Katherine Zachary, Nissan spokesperson, in an interview with PluginCars.com (our sister site). “Beyond that, it’s too soon to be able to predict the impact.” A shipment of more than 600 Nissan LEAFs destined for the U.S. left port in Japan on March 10, just prior to the earthquake, and will arrive as scheduled.

Supplies of small fuel-efficient conventional models, such as the Toyota Yaris, Scion xB and xD, and Honda Fit, could also be affected.