"Extra downforce" refers to the increase in the force pushing a vehicle or object down towards the ground. This helps improve stability and traction, especially at higher speeds. Full definition
Vettel was driving Ferrari's 2017 test mule — a 2015 Ferrari SF15 - T with extra downforce added to simulate the new cars — to test Pirelli's 2017 - spec wet - weather tyres. (wtf1.com)
Matte - finish carbon also graces the redesigned front spoiler lip and the 3 / 8th of an inch (10 mm) taller rear spoiler lip — which both enhance aerodynamics and provide extra downforce. (ausmotive.com)
This creates about 24 pounds of extra downforce at 80 mph, helping give the car enhanced grip. (topspeed.com)