How does the thin air affect cars at Mexico?

With its unique set of circumstances due to its altitude, the Hermanos Rodriguez track poses an enormous challenge for engineers to find the optimal cooling level for F1 cars.

Mexico City is located at over 2000 metres above sea level and the rarified air has an influence on car performance, reducing the aerodynamic downforce generated by the cars. One of the consequences of this is that top speeds reached are very high, despite a configuration that actually looks typical of tracks that require maximum downforce – the speed record was set here in 2016 when Valtteri Bottas in the Williams-Mercedes was clocked at 372.5 km/h.

Furthermore, on the longest straights, the main one and the one between turns 3 and 4, the surface temperature of the tyres tends to drop pretty quickly and the drivers have to be very careful when braking, especially at turn 1, to avoid locking the wheels and therefore damaging the tyres.

The Hermanos Rodriguez track is 4.304 km long, with 17 corners and a surface that is low in terms of its severity on tyres. This year the promoter has resurfaced the section between turns 12 and 15 in the third sector. The very smooth asphalt and the fact the track is hardly used means that grip levels are rather low at the start of the weekend and track evolution is very marked, rubbering in the more the cars run.

Asked to explain what it means to drive in thin air, US GP winner Charles Leclerc noted that it presents a huge difference, mainly in terms of cooling.

"That makes obviously a big difference for the downforce and for the cooling. So in terms of downforce, you have a lot less downforce compared to a normal track at sea level altitude, which means that you slide a lot more. And then for the cooling, it's a lot more difficult to actually cool the brakes, the engine. It's very difficult.

"And for us as well, the heart rate goes a little bit higher compared to other races, but it's not the most tiring and physical racetrack on that side. It's not that much of a problem. However, for the car, it's a very tough race for the car most especially for the cooling. So this will be obviously the main topic for this weekend.

"And then the very low grip but that is I will say similar to maybe a track like Monza. However, we are driving with probably the maximum downforce that we can put on the car but that results in having the same grip as on a track like Monza where we run minimum downforce.

"So it's a bit strange, as a driver, the first time you drive here because it's not something that you expect to feel that much. However, it's cool. It makes it a little bit different and it's different challenges and as a team you've got to adapt quickly," the Monegasque concluded.

Explaining the differences between the circumstances in Mexico City and in "usual" events, Sauber driver Zhou Guanyu noted that overheating is the most obvious challenge.

"Yeah, I think, you know, the biggest thing I felt was that probably from the first year I was driving here, from FP1 to qualifying, the grip, actually you're gaining a little bit, but compared to most of the tracks, for example, you actually doesn't really feel the track evolution that extreme.

"And then, like Charles mentioned, firstly, with the cooling in the race, it’s a big issue for the engine, for the gearbox, for the brakes, that's very easy to be overheating.

"And then on the other side, with the massive straight, DRS detection, you're actually not getting that much tow effect and slipstream like you expected at normal tracks. So that's probably the biggest difference. And yeah, the rest is all quite similar, to be honest," Zhou added.