The top segment at the auction, in terms of price increases, during the last month of 2014 was the midsize car, but it was the No. 2 segment on the list that had analysts with Kelley Blue Book a bit surprised, given the fuel-price climate.

With an 0.8-percent hike in auction price, the subcompact car trailed only the midsize car (up 0.9 percent) in the rankings of the five best-performing segments (based on increases in Kelly Blue Book Auction Value for 2011–2013 model-year vehicles).

This occurred amid average gas prices falling to a new national low of $2.49 per gallon in December, KBB said, citing data from the U.S. Energy Information Administration.

“The real surprise came from the strength we’re seeing in the subcompact car segment,” KBB analyst Sean Foyil said in the latest Blue Book Market Report from KBB. “Typically, as fuel prices dip, we see the more fuel-efficient segments take the largest hit, and with fuel prices reaching a three-year low, it’s surprising to see the smaller vehicles holding demand.”

Perhaps just as odd is what happened in the midsize car segment:  prices were up even though auction volume for the midsize car segment increased, as well, according to the report.

After the midsize and compact cars, the next strongest segment gains in the top five rankings were for the compact SUV/crossover and compact cars (both up 0.6 percent), followed by the luxury compact SUV/crossover (up 0.4 percent).

Conversely, the biggest declines were seen in the sporty compact cars (down 7.1 percent), followed by the electric vehicles (down 3.8 percent), minivans/vans (down 2.1 percent), high-performance cars (down 2.0 percent) and luxury cars (down 1.8 percent).

One of the segments that KBB found to be stable last month was the full-size truck. Its auction values in December showed just a 0.9-percent month-over-month decline and were ahead 3.0 percent year-over-year, even though the housing construction market had softened a bit the month before.

Specifically, KBB said the seasonally adjusted annual rate for privately owned housing units at the end of November was 0.2 percent softer than a year earlier and 1.4 percent weaker than a month earlier.

It was also the first time in six months that the housing unit SAAR had dipped on a year-over-year basis, the report said.

So why did full-size values remain so calm? KBB suggests it could have something to do with the low fuel costs mentioned earlier and models like the revamped Ford F-150 bringing some buzz to the segment.