Daycab and construction trucks behave differently than highway tractors in the used commercial truck market, say analysts at NADA Used Car Guide, a division of J.D. Power and Associates. The NADA report says that last year the typical used daycab vehicle sold at retail when it was just over 100 months old and had 425,000 miles.

This means daycabs are 28 months older with 65,000 fewer miles than the typical sleeper tractor. Original owners hold on to daycabs longer than sleepers, and they accumulate fewer miles per year.

Adjusted for mileage, 3- to 5-year-old daycabs sold for an average of 8% less money than their sleeper counterparts, all else being equal, said Chris Visser, senior commercial truck analyst at NADA Used Car Guide.

Like highway tractors, daycabs have become more plentiful, which has, or will, reduce prices for buyers. On the other hand, demand also seems somewhat less.

"The devaluation in the wholesale channel has not yet fully carried over to the retail channel,” Visser said. “We expect this price difference to shrink going forward due to the widening supply gap between sleepers and daycabs."

The January report summed up the market performance of construction trucks during 2015 as being very similar to their run in 2014. On average, the typical construction truck sold in 2015 was 128 months old and had just over 250,000 miles.

Compared to 2014, trucks sold were 8 months newer and had about 35,000 fewer miles. Universal average pricing was nearly identical, at just over $63,000 in both years. Overall, there were about 7% fewer construction trucks sold in 2015 than 2014.

Trucks of model year 2007 saw the highest sales volume in both periods, mainly because the period was the last high-build year before the recession. Availability of newer trucks improved in 2015, with the 2009 and 2010 model years seeing the most notable increase year over year.

This increased supply resulted in notable price erosion for 6- and 7-year-old trucks. The average 6-year-old construction truck in 2015 brought 6.6% less money compared to 2014, while the average 7-year-old unit brought 7.4% less.

The report concludes availability of newer trucks should continue to improve, as the higher-build 2012 and 2013 model years continue to return to the secondary market in greater numbers. Demand for construction trucks by sector should run slightly behind 2015 over the next few quarters due to slowing economic conditions.

Read the full January 2015 Commercial Truck Guidelines Report from J.D. Power and Associates here.