Keep the air from getting turbulent underneath the car as far as the rear spoiler or rear wing, that is to keep down force really on the back tires for traction mostly.
防止空气在汽车下方湍流直至后扰流板或尾翼，这是为了保持下压力真正在后轮胎上以获得牵引力。
Rear wing
原声例句
连线杂志
古生物经典纪录片
NARRATOR: In his first paper, Xu himself assumed that Microraptor would have to splay its legs out to the side to form the rear wings.
旁白：在他的第一篇论文中，徐本人认为小盗龙必须将腿向侧面张开才能形成后翼。
英语百科
Spoiler (automotive)
A spoiler is an automotive aerodynamic device whose intended design function is to 'spoil' unfavorable air movement across a body of a vehicle in motion, usually described as turbulence or drag. Spoilers on the front of a vehicle are often called air dams. Spoilers are often fitted to race and high-performance sports cars, although they have become common on passenger vehicles as well. Some spoilers are added to cars primarily for styling purposes and have either little aerodynamic benefit or even make the aerodynamics worse.