Used vehicles sold at auction declined 1.5% in value in September — a pace of depreciation relatively unchanged from August — in a month that saw relative strength in some truck segments and compact cars continue their slide, according to Black Book.

Vehicles from the 2010 to 2014 model years should close out 2015 with depreciation near 14%, which falls in line with the pre-recession range of 15% to 18% per year.

In September, compact cars led all vehicle categories with the highest depreciation at 3.7% in a category that includes the Buick Verano, Chevrolet Cobalt, Chevrolet Cruze, Dodge Dart, Ford C-Max, and Ford Focus. The category fell 16.9% to $8,923 from a year ago.

Truck categories bolstered the month, including full-size SUVs and full-size passenger vans, which tied for the lowest depreciation of 0.5%. Full-size SUVs such as the Chevrolet Suburban, Chevrolet Tahoe, Dodge Durango, and Ford Expedition fell 3.7% to $26,512 from a year ago.

Other categories showing relative strength included full-size pickups, mid-size pickups, and mid-size SUVs. These categories fell 0.6% to $24,064, 0.6% $16,763, and 0.8% to $21,850 from August respectively.

Other notable trends include compact pickups having the lowest 12-month moving depreciation average of 2.9%, which is a lower price drop than compact cars over the past 30 days.

Premium sporty cars fell 1.2% on the month and led car segments with the lowest depreciation. This segment includes the Audi R8, BMW 6 Series, Cadillac XLR, Dodge Viper, and the Mercedes-Benz CL Class. This segment fell 14.2% from a year ago to $43,253.

"Overall vehicle depreciation continues to hold up well, especially as we near the part of the year where heavier price drops are typically expected," said Anil Goyal, Black Book's vice president of automotive valuation and analytics. "It's very telling of the disparity between cars and trucks to see that we have some truck segments showing lower annual depreciation than what cars are seeing on a monthly level."