Used vehicles increased 0.4% in value in April, as buyers boosted the value of smaller cars, which have begun to shrug off several years of heavier declines, according to Black Book.

All cars increased in value by 0.7% compared with trucks, which saw a 0.3% increase. Vehicles from the 2011 to 2015 model years fell 16.9% in value from a year ago.

"Clearly we’ve had a stronger-than-expected spring this year, particularly in comparison to the last few spring seasons," said Anil Goyal, Black Book's senior vice president of automotive valuation and analytics. "We attribute much of this year’s strength to smaller car values which have experienced significant depreciation in the last few years and are most likely viewed as a bargain to many buyers right now."

Six of Black Book's 22 vehicle segments depreciated in value in April, including premium sporty cars, compact vans, full-size luxury CUV/SUV, full-size vans, subcompact crossovers and subcompact luxury CUVs. Of those vehicle categories, the full-size luxury CUV/SUV segment saw the most depreciation at 0.5%.

Full-size vans have depreciated 0.4% to $17,424, while compact vans declined 0.3% in value to $9,878 in the past month. Full-size pickups increased 0.4% to $22,223, while small pickups increased 0.7% to $18,911. Compact SUVs were flat at $12,578.