* Wants to make sure it can process all its sales in time

* Sold more than 10,500 cars, trucks with clunker rebates

AutoNation Inc (AN.N), the largest U.S. chain of auto dealers, decided to end its cash for clunkers rebates as of Friday night, three days ahead of the government's Monday deadline, The Wall Street Journal reported.

The program, aimed at boosting vehicle sales while helping the environment, offers rebates of up to $4,500 to car buyers trading in older, fuel-thirsty vehicles.

AutoNation, which has sold more than 10,500 cars and trucks with clunker rebates, wanted to make sure it could process all of its sales by the time the program officially ends at 8 p.m. EDT on Monday, according to the report, which cited an AutoNation spokesman.

AutoNation spokesman could not immediately be reached for comment on Saturday.

Lawmakers and the Obama administration had to scramble earlier this month to add $2 billion in funding after the program's initial $1 billion was quickly exhausted.

The program has faced some complaints from dealers who have reported delays in government reimbursements and problems finalizing paperwork.

Fort Lauderdale, Florida-based AutoNation operates 220 dealerships in 15 states across the South and West. (Reporting by Matthew Lewis; Editing by Toni Reinhold)