If you are a NASCAR fan, then I’m sure you have heard about side drafting. No, it’s not when you drive past a truck and almost get blown off the road. That’s wind blast. And it’s not when your buddy swoops in and steals the girl you’ve been talking to at the bar. Side drafting is actually a very effective way to slow your opponent by making their car draggy. Here’s how it works.
As a driver approaches another car, they will strategically position their car on the rear quarter of the car they are trying to pass. Strategically positioning the front bumper of the car on the rear quarter creates a big pressure region from the front bumper. This pressure acts like an air damn to push the air in the direction of less pressure onto the lead cars rear spoiler increasing the air drag on the lead car.
This works because the NASCAR body creates quite a big high pressure region in front of the car due to the bluff shape of the front bumper. This same shape helps to funnel air under the splitter but also helps to redirect air for side drafting!