Changing consumer behavior is forcing wholesale market experts to modify how they track pricing shifts.

While recapping what happened in December, J.D. Power Valuation Services shared its latest wholesale price expectations for 2018, along with what analysts suspect will happen when the January data becomes available.

According to the latest installment of Guidelines, J.D. Power Valuation Services projected that January wholesale prices for vehicles up to 8 years in age will soften by 0.5 percent to 1 percent.

Despite the dip projected for the opening month of 2018, analysts suspect that their full-year price projections will stay “relatively flat” when compared to 2017 movements.

Last year closed with J.D. Power Valuation Services — formerly NADA Used Car Guide — seeing average wholesale prices dropping by 2.3 percent. The movement left J.D. Power Valuation Services’ Seasonally Adjusted Used Vehicle Price Index at 114.8, marking a drop of 0.9 percent.

For all of 2017, the index fell 3 percent year-over-year, according to the report, which also shared the modifications J.D. Power Valuation Services made to its evaluations.

“Compared to earlier time periods, the last few years has shown a significant divergence in price behaviors between cars and light trucks,” analysts said in Guidelines.

“Trucks (CUVs, SUVs and pickups) exhibit different depreciation behaviors and different seasonal price variations, and the magnitude of these differences have grown over time,” they continued. “Because of this, we have separated the portion of the index calculation that account for depreciation and seasonal price variations into a calibration for cars and a calibration for trucks.

This allow for a more accurate accounting of these factors, which in turn allows for a more accurate accounting of the actual movement in prices outside of these factors,” analysts went on to say.

The modifications to the reporting touched on another aspect, too.

“In addition, a careful reassessment was made of the appropriate seasonal price variation assumptions in light of the reduction in observed seasonal peaks and troughs of the last two calendar years,” analysts said.

“The primary result of this assessment as it concerns recent price movements, is a reduction in the size of price movements in the seasonally adjusted series for the spring and fall of 2017,” they added.

After the explanations, J.D. Power Valuation Services turned back to its December data.

Analysts found the last month of 2017 produced losses at the level larger on average than historic norms.

Luxury utility prices fell by a “significant” 4.2 percent — a level 3 percentage points higher than what analysts spotted during the past five years. The trend was especially noticeable for model years 2014 through 2017.

A specific vehicle example J.D. Power Valuation Services mentioned was the Mercedes-Benz GL. As auction volume for these units rose 8 percent, prices dropped by 5 percent.

Analysts also noted that compact luxury utilities softened by a healthy figure in December, as well, sliding by 4.1 percent.

The two other luxury segments J.D. Power Valuation Services watches dropped by similar rates. Luxury midsize utilities dipped by 3 percent, and luxury midsize cars were off by 3.4 percent.

Over on the mainstream side of the market, the report showed large utilities paced the December decliners, dropping by 4.2 percent as large full-size units from General Motors took the brunt of that decrease. For example, analysts mentioned the 2014 Chevrolet Suburban fell by 8 percent, while the 2014 GMC Yukon XL decreased by 7 percent.

Analysts also spotted a 3.4-percent price decline for subcompact cars in December; a reading 2.4 percentage points higher than what they typically saw in the closing month of a year going back to 2012.

J.D. Power Valuation Services closed by pointing out that large pickups continue to “outperform the market” since prices for these units dipped by just 1.6 percent in December.