FORT LAUDERDALE, Fla. -

AutoNation’s fourth quarter results are in as of Thursday – and taking a look at its consolidated used-vehicle units retailed, the United States’ largest automotive group moved 53,920 used vehicles last quarter, a slight, 386-unit increase over Q4 2014.

Those sales contributed to a total of 227,290 used units sold for all of AutoNation’s stores in 2015, a 5.8-percent increase over the previous year (when the group sold 214,910 used units).

The group’s used-vehicle revenue, including used vehicles both retailed and wholesaled, increased by 4.4 percent in Q4 2015 (compared to Q4 2014) to roughly $1.15 billion. By the same metric, AutoNation’s full-year used-vehicle revenue came in at roughly $4.77 billion, an 8.7-percent increase compared to the full-year results for 2014.

However, AutoNation did experience decreases in both new- and used-vehicle gross profits last quarter. Used-vehicle gross profit, also including both retail and wholesale used vehicles, fell year-over-year by 14.6 percent to $75.7 million last quarter. By the same metric, the group’s full-year 2015 gross profit for used vehicles fell by 1.9 percent to $353.7 million, compared to 2014’s results.

Mike Jackson, AutoNation’s chairman, chief executive officer and president, summed up the group’s overall condition in a statement included with the company’s 2015 results.

"In the fourth quarter, new and used vehicle margins on a combined basis declined by $217 per vehicle retailed, or 11 percent, as compared to the fourth quarter of 2014,” Jackson said. “As of year-end, our new vehicle inventories increased 13 percent on a same store basis, as compared to the prior year, driven by a 49 percent increase in premium luxury inventories. We have begun, and will continue through the first quarter, to take the necessary steps to align our costs, inventory, and pricing strategy to adjust to the current market."

Gross profit per used unit retailed was down slightly on both a quarter-over-quarter and year-over-year basis, ending the year at an average of $1,441 per vehicle in Q4 and $1,577 per vehicle for the year.

Looking at the company’s overall gross profit mixes, used-vehicle sales made up 10.8 percent of AutoNation’s mix for the year, down from 12.1 percent in 2014. From a retail perspective, AutoNation continues to make the majority of its profits from parts and service (41 percent of the mix in 2015), F&I (26.6 percent) and new-vehicle sales (20.6 percent).

AutoNation closed the year with 43 days of used-vehicle supply.

Editor's Note: For more insight into AutoNation's Q4 and full-year results, stay tuned to Monday's Auto Remarketing Today.