GM: Sticking Rudolf's nose on your car hurts fuel economy

Rudolf the Red Nosed Reindeer may be perfectly suited to guiding sleighs in inclement weather, but if you played Santa: The Home Game this year, the chances are the little guy took some of the edge off of your fuel economy. That’s according to GM, which tested a GMC Terrain in a wind tunnel to gauge the effects of antlers and a reindeer nose. For science.

GM’s intent was to underscore the improved aerodynamics of its new-for-2018 Terrain, and to do so, it went to Smyrna, Georgia, accessorized its new SUV with a host of holiday decorations, and did some proper scientific testing. The results are pretty cut and dry, and hardly surprising, given the amount of time aerodynamicists spend honing the shape of every vehicle to maximize efficiency.

Specifically, reindeer antlers and a puffy red nose combine to cost about one mile per gallon at highway speeds. A bow on the roof of the vehicle, however, lowers fuel economy by a full three miles per gallon. The biggest hit, by far, though, is a Christmas tree on top, which nearly doubles the amount of aerodynamic drag on the Terrain, and cuts mileage by as much as 30 percent. Perhaps surprisingly, a wreath on the front of the vehicle resulted in no measurable impact to fuel economy.

While it’s obviously too late to recoup any losses from this past holiday season, it’s definitely worth filing this data away for next time.