How Drafting a Car Works

Drafting—also called slipstreaming—works by having a trailing car tuck into the low-pressure wake behind a lead car, where the air is less resistant; this reduces aerodynamic drag on the follower (and slightly on the leader at very close gaps), allowing higher speeds and lower fuel use. In practical terms, racers exploit drafting to pass on straights, while everyday drivers should avoid it on public roads because the close distances required are unsafe and often illegal.

The physics that make drafting possible

At speed, a vehicle pushes air aside, creating a high-pressure zone up front and a turbulent, low-pressure wake behind. The trailing car that moves into this wake faces less headwind and therefore less drag. The effect depends on speed, car shapes, and the gap between vehicles.

Below is a concise breakdown of the aerodynamic chain of events involved in drafting.

• Displaced air: The lead car forces air outward and leaves a turbulent wake with lower average pressure behind it.
• Reduced relative wind: The trailing car in that wake experiences a smaller pressure difference from front to rear, cutting drag.
• Power and fuel savings: Aerodynamic power demand scales with the cube of speed; lowering drag meaningfully reduces the horsepower (and fuel) needed to maintain speed.
• Mutual effects: At very small gaps, the follower “fills in” some of the leader’s wake, slightly raising pressure behind the lead car and trimming its base drag.
• Side effects: Turbulence can reduce the follower’s cooling airflow and, in downforce-dependent race cars, rob front-end grip in corners (“dirty air”).

Taken together, these effects explain why drafting boosts straight-line speed and efficiency, but can compromise handling and cooling if overused or attempted in the wrong places.

What each car gains—and gives up

Drafting impacts the leader and the follower differently; the balance changes with vehicle design and spacing.

• Follower benefits: Substantially less drag in the wake, enabling higher top speed or throttle savings. On highways, tightly spaced platoons in controlled tests can cut the follower’s fuel use by 10–20% or more; on racetracks, the follower accelerates faster on straights.
• Leader effects: At very close distances, the leader’s wake pressure rises, trimming its drag a little. In some stock-car “tandem” situations, both cars become faster as a pair. With larger gaps, the leader sees little benefit.
• Handling trade-offs: In open-wheel racing (e.g., Formula 1), the follower’s front wing and underfloor see disturbed flow, reducing downforce in corners; since 2022, revised ground-effect designs have narrowed the wake to help cars follow, but slipstream strength on straights is somewhat reduced compared with pre-2022.
• Thermal concerns: Reduced clean airflow can raise engine, brake, and tire temperatures for the follower, especially when tucked in for long periods.

In short, the follower usually gains more than the leader on straights, but the turbulence and heat can cost the follower in cornering or reliability if mismanaged.

Drafting in different contexts

Motorsports

On ovals and long straights, drivers time moves to sit in a rival’s wake and then pull out to pass. NASCAR’s “pack drafting” at superspeedways builds massive runs as multiple cars link wakes; the current Next Gen car still produces packs, though bumper shapes and cooling have curtailed the prolonged “tandem” pushing seen a decade ago. In Formula 1, drivers deploy slipstreaming mainly on straights; the sport’s DRS (drag reduction system) further cuts the following car’s wing drag when within one second in designated zones, helping offset “dirty air” in corners.

Public roads

While the physics are the same, the safety calculus is not. Meaningful fuel savings for a passenger car following another vehicle generally require gaps far smaller than the safe stopping distance at highway speeds. Tailgating—especially behind trucks to “surf” their wake—dramatically shortens reaction time, obscures visibility, invites debris strikes, and is illegal in many jurisdictions.

Trucks and automated platooning

Professional trials with vehicle-to-vehicle communication and automated control can keep heavy trucks in stable formations at small but managed gaps, improving economy for all participants. European multi-brand trials (e.g., the ENSEMBLE project concluded in 2023) reported fuel savings on the order of roughly 5–10% for lead trucks and 10–15% for followers at highway speeds. Commercial deployments remain limited and heavily regulated; consumer vehicles should not attempt tight-gap drafting without automation designed for that purpose.

How racers actually use it

On track, drafting is a tool to set up passes without overspending tire or fuel. The outline below summarizes common race-craft steps for using the slipstream on a straight.

1. Close the gap in a preceding corner exit to enter the lead car’s wake as early as possible.
2. Sit in the slipstream on the straight to build a speed delta while monitoring temps and steering stability in turbulent air.
3. Pull out of line just before braking—early enough to avoid aero push and to regain clean air for cooling and downforce.
4. Complete the pass under braking or into the next corner entry, then return to the ideal line.

The choreography aims to maximize straight-line benefit while minimizing the handling and thermal penalties that come with prolonged wake exposure.

Safety and legal reality on public roads

Because effective drafting demands small headway at high speed, it is fundamentally unsafe for everyday driving. The points below capture the key risks and norms.

• Stopping distance: At 70 mph (113 km/h), even a one-second gap means over 100 feet before you can react; safe following guidance is typically two or more seconds, which erases most drafting gains.
• Visibility and debris: Following closely behind large vehicles hides hazards and increases the chance of stone chips or tire-tread impacts.
• Law and liability: Tailgating is citable in many regions; in a crash, the follower is often deemed at fault.
• Practical economy: Proper tire pressure, steady speeds, and anticipating traffic yield safer, comparable fuel savings without the risk.

For everyday motorists, the modest theoretical fuel gains from tight-gap drafting are outweighed by the danger and legal exposure.

Numbers that anchor the concept

Drafting effects scale with speed and vehicle shape. At highway speeds, aerodynamic drag can account for the majority of a modern car’s resistive forces; cutting that drag even modestly yields measurable savings. In controlled testing, very small gaps can reduce the follower’s fuel use by double-digit percentages, and in racing, a strong tow can add several mph (or km/h) to top speed on long straights. But outside controlled environments with trained drivers and spotters—or automated platooning systems—those gaps are not survivable when something goes wrong.

Bottom line

Drafting works by hiding in another vehicle’s turbulent wake to reduce aerodynamic drag. It’s a powerful, carefully managed strategy in racing and a research-backed energy saver in tightly controlled truck platoons. On public roads, though, the close distances required make it unsafe and often unlawful, and safer fuel-saving habits are preferable.

Summary

Drafting reduces drag for a trailing vehicle by riding in the low-pressure wake of a lead vehicle; at very close spacing, the leader can also see a small drag reduction. Racers use it to gain speed on straights and set up passes, balancing benefits against dirty air and cooling limits. Automated truck platooning can safely harvest similar gains, but everyday drivers should not draft: the necessary gaps are unsafe and typically illegal, and there are safer ways to save fuel.

Does drafting make you go faster?

A person riding in a paceline will use at least 25% less energy for the same speed compared to someone riding alone. Riding in a pack boosts this energy savings up to as much as 30 to 40%. So, drafting will allow you to ride 2-4 mph faster than you can alone, for about the same energy output.

Is bump drafting legal?

Bump drafting is legal in some forms of NASCAR racing, particularly the Cup Series, but is generally banned in many other motorsport series and forms of simulation racing due to safety concerns. While normal drafting is permitted, more aggressive “tandem drafting,” where cars maintain contact for longer periods, was banned by NASCAR after an incident in 2013 that injured spectators. The legality and acceptability of bump drafting can also depend on the specific race, the rules of the series, and the discretion of officials.
 
Where bump drafting is legal:

• NASCAR Cup Series: In NASCAR’s top series, bump drafting is permitted on superspeedways. 
• Spec Miata racing: Some community forums suggest that bump drafting is considered permissible and is a practical application of the rules that allows for cooperation. 

Where bump drafting is not legal:

• Other racing series: Opens in new tabBump drafting is banned from most forms of motorsport, with the technique often outlawed due to the risks of serious accidents. 
• Formula 1: Opens in new tabThe technique is not used and is generally considered dangerous in F1, partly due to the risk of losing control. 
• Some sim racing: Opens in new tabBump drafting is banned in certain sim racing leagues, particularly in European-based lobbies, and can also impact a player’s safety rating in some platforms. 

Risks and nuances of bump drafting:

• High speed and risk of accidents: It is a risky maneuver that can cause cars to lose traction and spin out, potentially leading to major wrecks. 
• Distinction from “tandem drafting”: Tandem drafting, which involves sustained contact, is different from a brief push and is more strictly prohibited. 
• Enforcement: In NASCAR, while bump drafting is allowed, officials may still police aggressive driving, and a poorly executed bump can lead to penalties. 

How does auto drafting work?

When using the “Autopick Draft” option, the system automatically drafts players to each team in the league on a scheduled draft date so team managers don’t have to be online during the draft. Team managers can pre-rank players in their draft lists to enhance their chances of getting their dream roster.

How does car drafting work?

Drafting refers to a strategic racing technique where a vehicle closely follows behind another, taking advantage of reduced air resistance or drag created by the lead vehicle.