Ford Motor Co. (F) will kill off the Ford Excursion (search), its largest sport utility vehicle and a lightning rod for criticism from environmental groups, next year, a source familiar with the plan said on Monday.

The mammoth vehicle will stop rolling off the assembly line in September, as Ford moves to free up production capacity for the refreshed Super Duty pickup truck (search), said the source, on condition of anonymity.

The Excursion and Ford Super Duty F-Series pickups are assembled at the automaker's Louisville, Kentucky, truck plant.

A Ford spokesman declined to comment on the product plan.

Ford sources had said in 2002 that the company would discontinue the 19-foot Excursion, but it wound up getting an extended lease on life.

The second-largest U.S. automaker is planning to fill the gap in its full-size product lineup with an extended version of its Expedition SUV (search), the source said.

U.S. sales of the Excursion, which was launched in 1999, are down 25 percent so far this year. The Sierra Club, which dubbed the Excursion the "Ford Valdez" after the infamous Alaskan oil spill, called it an environmental disaster because of its poor fuel economy rating.

Official gas mileage figures are not available from Ford or the Environmental Protection Agency, but a review on Kelly Blue Book's Web site says the Excursion gets about 14 miles per gallon on the highway and 10 miles per gallon in the city.

Apart from the Excursion, a mid-size SUV from Ford's lineup will also be killed.

Lincoln Aviator, which made its debut in 2001, will be replaced with a car-based SUV in 2006, said Lincoln spokeswoman Sara Tatchio. She declined to say exactly when production of the Aviator will stop.

U.S. sales of the Aviator are down 20.3 percent year-to-date.