The average prices for used fleet vehicles sold at auction increased 6.2% to $12,464 in 2018, despite a weaker finish to the year that saw a 0.4% decline in December, according to Tom Kontos, KAR Auction Services' chief economist.

Vehicles from fleet remarketers outperformed the market at large, which was 1.7% lower than December 2017 with an average price of $10,620. However, December sales increased 0.2% from November, which saw a softening of used vehicle values.

"On average, truck prices softened more than car prices, which were up significantly versus November, though down year-over-year," Kontos wrote in his monthly commentary. "When holding constant for sale type, model-year age, mileage, and model class segment, prices were up significantly on a year-over-year basis for both midsize cars and midsize SUVs."

The overall performance of these vehicle categories, which represent more popular fleet segments, performed well in 2018. Midsize cars increased 5.7% to $10,985 in December, while midsize SUVs increased 8.6% to $18,855.

Fleet consignors saw stronger pricing that their colleagues who were remarketing manufacturer or dealer vehicles. Vehicles from manufacturers fell 4.5% from November and 4% from December 2017. Dealer vehicles fell 0.4% from November and 2.2% from December 2017. Sales of certified pre-owned vehicles increased 8.4% from November and 2.1% from December of 2017. For the full year, CPO values again reached record levels, Kontos said.