STAMFORD, Conn. -

Auction prices were still moving up in March as tax-season rate highs lingered a bit longer than usual, but the spike isn’t here to stay.

According to RVI’s first-quarter newsletter, prices increased by 2.5 percent from February and 4.8 percent year-over-year last month (after adjusting for MSRP, the price change is slightly less, with an increase of 2.2 percent from February and 1.7 percent year-over-year).

And though spring has seen auction prices remain high, they are predicted to decline slightly due to seasonality in the short-term, and RVI offered a long-term outlook, as well. Used-car prices are expected to begin declining in 2015, and by 2017, the company expects used-car prices to drop by 5 percent.

The midsize sedans have seen auction prices rise the most since February, according to RVI, with prices spiking by 3 percent within the segment.

But just as the overall industry price hikes are not predicted to stick around, neither is the spike within this segment.

“The supply of midsize sedans will continue to increase through 2018 and this increased supply will lead to a drop in used car prices for the segment,” RVI analysts reported.  “By the end of 2017, used-car prices within the segment are expected to drop below 4 percent of current levels.”

This trend as well as overall industry predictions regarding upcoming used-price drops are in part due to the fact to an influx of off-lease vehicles expected to start flooding the market this year.

And lease penetration rates continue to rise, boding well for off-lease supply in the next three to five years, as well.

RVI noted that lease penetration “continues to grow and is expected to increase for 2014 and 2015 model-year vehicles.”

In fact, lease penetration increased in Q4 of 2013 to 24.1 percent of new-vehicle sales. RVI offered the following comparison: during the fourth quarter of 2012, the lease penetration rate as at 20.8 percent of retail sales.

As far as which brands are seeing the highest leasing rates, Infiniti leads the pack with a 61 percent lease penetration rate in Q4 2013.

Volkswagen has the highest lease penetration among non-luxury brands with a rate of 36 percent, according to RVI.