It takes an awful lot of confidence to design your Formula One car to run specifically at the front, but that’s just what the Mercedes team has done. The only problem is—as we saw during the Italian Grand Prix—that the cars struggle desperately when they’re following in another driver’s dity air. Here’s what’s going on.

In Italy, Valtteri Bottas had a terrible start that saw him slip down the grid. Mired in the middle of the pack, Bottas struggled to pass the cars in front of him despite the fact that he was so much faster than most of them in qualifying. You’d think he’d be able to fly past them—but, as with anything in F1, things are a lot more complex than they appear on the surface. And, as you’d expect, it comes down to a whole lot of technology unavailable to the naked eye.

You can grab a really great visual of what’s going on courtesy of on YouTube, who does an incredible job illustrating F1's technical concepts.

Basically, Bottas’s car got too hot. In a normal race, where the Mercedes cars either lead the field or settle up front with a significant gap between it and the car ahead, there’s no reason a car would get too hot. It’ll be washed in untouched, cool air—there’s nothing to worry about. But stick a Mercedes behind a bunch of other cars, and it becomes obvious the team didn’t anticipate this.

Cars are hot. F1 cars are powered, in part, by literal combustion, and that kind of heat grows during races. When car parts get hot, they expand, which, if you have not guessed, is not ideal in a race car that’s designed in a very particular way. Every single team has to manage overheating, but most teams expect some degree of running in heavy traffic and design their cars to reflect that. Not so with Mercedes.

F1 cars use liquid cooling in its power units, which essentially means that cool water is pumped through special tubes in the power unit. The cool water pulls some of the heat from the engine and keeps it running at a regulated temperature. That heated up water is pushed into a radiator, and the radiator disperses the heat into the air. Those radiators are designed to take up plenty of surface area because the more surface there is, the faster and more efficiently the water will cool.

You’ll have to watch the video to get a better understanding of where the air is channelled, but there are multiple outlets for warm air. Unfortunately, that creates drag. You want the air to slide over the car, not be sucked up by the car. There’s a balance between how much cooling you can do before it too negatively affects the aerodynamics. And then there are a lot of other factors to take into account: ambient temperature, track speeds, lengths of straights, and how often you’ll be stuck behind a different car.

When you’re at the head of the field, you have plenty of cool air to take advantage of. Stuck behind another car, though, your cool air channel is disturbed, and you’re also receiving that competitor’s hot air. As a result, you can’t just stick behind the car in front of you. You might have to slow down in order to prevent your car from getting hot. You might have to take a less ideal racing line.

Most teams design their cars with those aspects in mind. But Mercedes—a team that rarely ever ends up mired in the middle of the field battling cars for position—has made a trade-off. It has prioritized a smooth, aerodynamic shape in exchange for carving wider vents to suck up and push out air. Basically, Mercedes has decided that it will be more likely to lead the field than to battle for a mere top 10, and it has erred on the side of running a warmer car in order to capitalize on stronger aerodynamic performance.

Think about it: if you know you have, say, a 75 percent chance of qualifying on pole or leading the whole race, why should you impede your speed by preparing for an event that likely will not happen? As the past few years have shown, Mercedes really doesn’t need to worry about dirty air. Events like the race at Monza are fairly rare.

So, there you have it: Mercedes is so dominant that it doesn’t normally need to worry about what would happen if it were to be stuck behind eight other cars.