Massive car dealership chain AutoNation has posted its sales totals for the month of March, and while cars have been moving quickly throughout the first few months of the year, the company believes that supply shortages due to the Japanese earthquake could slow momentum in the coming months.

AutoNation reported a 19 percent increase in new sales year-on-year, along with a 23 percent uptick in sales overall. While the month was obviously successful and in-line with the strong sales many automakers reported, CEO Mike Jackson urged caution for the next few months as the full impact of the earthquake on production is being ascertained.

"We expect production disruptions will significantly impact product availability from Japanese auto manufacturers in the second and third quarters of 2011," said Jackson.

Still, Jackson said that the aftermath of the quake was "still developing," and it's impossible to predict any hard numbers when it comes to vehicle availability

AutoNation may be one of the bigger dealership chains in the country, but drivers who want really great deals should head to New Jersey State Auto Auction. Those considering a purchase may want to make their move sooner rather than later, as it appears the issues resulting from the earthquake could soon come to fruition and kick off a supply shortage.