What Is a Slipstream in F1? The Tow Explained | Formula Dream
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What Is a Slipstream in F1? The Tow, and F1's Closest Finish
The F1 slipstream, or tow, explained, the physics of how following closely cuts drag and adds speed, why it is the same wake as dirty air, the 1971 Monza classic it decided, and the 2019 farce it caused.
There is a strange contradiction at the heart of following another F1 car. In the corners, running close is a curse: the turbulent air ruins your grip. But on the straights, that exact same air is a gift, and it gives you free speed. That gift is the slipstream, or the tow, and drivers will risk almost anything to get it. It has produced the closest finish in the history of the sport, and once made an entire qualifying session collapse into farce. Here is how it works.
What is a slipstream?
As an F1 car powers down a straight, it has to shove a huge amount of air out of its way, and doing so leaves a pocket of
directly behind it, effectively a hole punched in the atmosphere. A car that tucks in close behind drops into that hole, and suddenly it is no longer fighting through undisturbed air. The
leading car has done the hard work
of parting the air; the following car gets to ride through the gap it left. Sitting in that pocket is called getting a
tow
or a slipstream.
The physics: someone else does the work
The reason it is worth so much comes down to drag. Most of the power an F1 car uses at top speed goes into simply pushing air aside. The lead car takes that full aerodynamic hit. The car behind, sitting in the wake, meets much less air resistance, so it needs less power to go the same speed. With drag slashed, it accelerates harder and reaches a higher top speed, without doing anything different with the engine. It is, quite literally, getting a free ride on the leading car's effort.
The leading car does the work of parting the air. The following car drops into the low-drag pocket in its wake and gets a free run of extra speed.
The same wake, opposite effect
Here is the part that ties it all together, and it is the single most useful idea in F1 aerodynamics. The slipstream is the exact same turbulent wake as dirty air, the thing that destroys a following car's grip in corners. The difference is entirely about what you need at the time. In a corner, you need clean air flowing over your wings and floor to make downforce, so the wake hurts you. On a straight, you do not need downforce at all, you just want low drag, so the wake helps you. One phenomenon, two completely opposite effects, depending only on whether you are turning or going straight.
How big is the advantage?
It depends on the track. The lower the downforce a circuit demands, the more the cars rely on low drag, and the bigger a tow becomes. At Monza, F1's fastest track, where teams trim their wings as flat as they dare, a good slipstream can be worth as much as half a second a lap. That is an enormous margin, easily the difference between pole position and the midfield.
Monza 1971: the closest finish in F1 history
Nowhere shows the power of the tow like Monza, and no race shows it like the 1971 Italian Grand Prix. Back then, before the chicanes were added, almost the entire lap was a flat-out dash, and the slipstream was everything. The lead swapped constantly as cars towed past one another down the straights, and it came down to a five-car sprint to the line. Peter Gethin won by one hundredth of a second from Ronnie Peterson, with the top five covered by just 0.61 seconds, still the closest finish Formula 1 has ever seen. It was, at the time, the fastest F1 race ever run. That is the slipstream at its purest: cars that could not escape each other, dragged together lap after lap by the air itself.
Monza 2019: the tow that broke qualifying
Because a tow is worth so much at Monza, nobody wants to be the car in front, handing a rival the benefit while getting nothing back. In the final part of qualifying in 2019, that logic broke the whole session. Every driver hung back out of the last corner, crawling at walking pace, each waiting for someone else to go ahead and provide the tow. They dawdled so long that the clock ran out, and eight of the ten drivers crossed the line just as the chequered flag fell, never getting to start their final lap. Only Charles Leclerc and Carlos Sainz made it round in time. It was faintly ridiculous, and it was the clearest proof imaginable of how much drivers value a slipstream: they will risk missing the flag entirely to get one.
The tow and overtaking today
In the modern era, the slipstream rarely works alone. A chasing driver uses the tow to close right up on the straight, then adds DRS, opening the rear wing to shed even more drag, and the two together are usually what completes an overtake. From 2026, with DRS replaced by active aerodynamics, the specific tools change, but the fundamental prize does not: get into the car ahead's wake on a straight, and the air itself will help sling you past.
See a one-second gap to scale
A tow only works inside about a second of the car ahead, and one second at racing speed is a surprising amount of track. Our Gap Visualizer turns the gap between any two cars into real metres, so you can see exactly how far a slipstreaming driver actually has to close.
Frequently asked questions
What is a slipstream in F1?
The pocket of low-pressure air behind a car. A following car that tucks into it meets much less drag, so it can accelerate harder and reach a higher top speed. It is also called a tow.
What is the difference between a slipstream and dirty air?
They are the same turbulent wake. On a straight it helps, cutting the following car's drag for more speed (slipstream). In a corner it hurts, robbing the following car of the clean airflow it needs for grip (dirty air).
How much is a tow worth in F1?
It depends on the track. At a low-downforce circuit like Monza, a good slipstream can be worth around half a second a lap.
What is F1's closest ever finish?
The 1971 Italian Grand Prix at Monza, decided by a five-car slipstream battle where Peter Gethin beat Ronnie Peterson by 0.01 seconds, with the top five covered by 0.61 seconds.
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