Rising used vehicle depreciation pulled average April values into the red in a month that's typically the last strong month of the spring season, according to Black Book.

Used vehicles from the 2010-2014 model years depreciated 0.1% in April from March and 17.1% from a year ago. Truck-based vehicles were flat at $18,046, while cars fell 0.3% to $11,495. The past 12 months have seen depreciation accellerate to 14.3% for trucks and 20.6% for cars.

"Almost a third of all vehicle segments saw an increase in value this month but we expect this volume of segment retention to subside moving through the remainder of the year," said Anil Goyal, vice president of automotive valuation and analytics. "As the supply levels for all used vehicles grow, we can expect to see a continued increased in overall depreciation moving forward."

Eight vehicle segments, including Full-Size Cars, saw value increases during the month. Other positive segments included Small Pickup Trucks, Mid-Size Cars, Full-Size Crossovers, Mid-Sized Crossovers, Sporty Cars, Sub-Compact Crossovers, and Compact Crossovers.

In a sign of the spring season, Full-Size Cars best retained their value in April at 1.3%. Vehicles in this segment include the Chevrolet Impala, Ford Taurus, Kia Cadenza, Nissan Maxima, Chrysler 300 and Toyota Avalon. Vehicles in this segment finished the month with an average price of $12,930, a 16.9% decline in value from year-ago levels.

In the van category, full-size vans declined 0.7% to $18,912 in April, while compact vans declined 1.8% to $9,670.