The long reign of Lexus atop the U.S. luxury car sales chart is set to come to an end this year, thanks to an aging lineup and production disruptions caused by the March 11th earthquake in Japan.

Lexus first hit the market in 1990 and after just 10 years, Lexus overtook Mercedes, BMW and Cadillac to become the top selling luxury make in the U.S.

The move put a halo on Toyota's overall image, and generated as much as half of its North American profits.

But now, thanks to shutdowns at Toyota plants in Japan, where all Lexus models except one, the RX 350, are made, threaten its already thin hopes of retaining its crown for the year.

In the first three months of this year, Lexus's U.S. sales declined 4.4%, despite a rise in overall auto sales. Among luxury brands, Lexus slipped to third place for the quarter, behind BMW and Mercedes-Benz.

One of those two will likely pick up the mantle for 2011.