The faster you go, the more your car has to overcome aerodynamic drag. That much is obvious. What might be more surprising, however, is that drag increases at the square of speed – if you're going 30 miles per hour and accelerate to 60 mph, you'd expect to encounter twice the air resistance, but in reality, there's four times as much. Slick aerodynamics are more important at higher speeds than anywhere else, and BMW has patented a solution that could make its wagons, hatchbacks, and SUVs even slicker on the freeway. And considering EVs like the iX3 are even more susceptible to wind resistance, the new tech could be a game changer for battery range. Sailing Through The Wind Published on March 5 at the German Patent and Trade Mark Office, the technology relies on a car with a roof and side-view mirrors, so it's probably pretty darn universal. At the top of the roof is a conventional rear spoiler, like you'd find on each of the automaker's SUVs, crossovers, and wagons, as well as its European-market hatchbacks. A series of telescoping panels deploys from underneath rear spoiler, however, bringing curved vertical fins with them to allow the roofline to taper rearward and down, turning the car's aerodynamic profile into more of a teardrop shape.German Patent and Trade Mark OfficeIn addition to the extending rear wing, the patent also describes telescoping aero trim for the side-view mirrors. As with the spoiler, the mirror surrounds move rearward once the vehicle is at a specific speed, reducing drag around the mirrors – a seemingly minor but important area that has more of an effect on wind resistance more than you'd expect since they stick out from the otherwise-smooth bodywork by several inches. The crisp edges on the ends of the spoiler and the mirrors provide a clean break from passing air, reducing low-pressure turbulence behind the car that causes additional drag. Big Benefits For Every Car, Bigger Benefits For EVs Internal combustion vehicles tend to be most efficient at freeway speeds, and reducing wind resistance will only make them thriftier when cruising down the Autobahn. Improving aero by even five percent – say, from the current X5 SUV's 0.33 drag coefficient (Cd) to 0.30 or 0.31 – could potentially improve efficiency by a few extra miles in each tank of fuel, especially if lots of those miles happen at higher speeds where the aero improvements would be most noticeable.BMWIn cars that are less efficient on the highway, like EVs and some hybrids, the aero tweaks could have even more of an effect. In electric cars, higher speeds affect range pretty badly, which is why aerodynamic efficiency is so important to EVs. The aforementioned iX3, for example, has a 0.27 Cd and an estimated range of about 400 miles in combined driving, meaning it can probably do about 360 or 370 miles on the highway alone. Dropping that coefficient to around 0.26 or 0.25 could put the highway range number closer to the combined estimate, improving efficiency overall.In a crossover-mad auto market, every little bit of progress could have a big effect on emissions and fuel consumption for a huge number of drivers. If every little bit helps, the BMW patent could have wide-reaching benefits for lots of motorists – and the world overall.Source: German Patent and Trade Mark Office
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