Mexico City F1 track's low grip level 'crazy' says Lewis Hamilton

F1 cars returned to action at the Mexican venue for the first time since 1992, with the new track surface and a lack of downforce due to the air quality at high altitude giving drivers little grip.

"It's very slippery, it's crazy out there because we're at so-high altitude," said Hamilton, who was fourth quickest on Friday.

"It's way worse grip than we have at Monza, so low.

"We're just sliding around, it's more like a kart track in the slow areas.

"It's like being on marbles, there is so little grip. It's fun though.

"The surface, because it's new, it has no rubber in it. It's getting better and better the more we drive."

Daniel Ricciardo added: "The track was always slippery, so there were many, many mistakes.

"Nearly every lap, you're making a mistake. You hope the grip's there, but it isn't.

"With the altitude we lose downforce - even though we've got more wing than Monza, the actual [downforce] numbers are less."

Sebastian Vettel said the lack of grip made the track slower to drive on than he was expecting.

"I think everybody was struggling to keep the car on the track," said the Ferrari driver.

"It's surprisingly low-speed overall, I was hoping for the fast corners to be a little bit quicker.

"But hopefully with more rubber on the track it will get a little bit better."

Jenson Button said the circuit was improving before rain hit at the end of second practice, and he was positive about the majority of the layout.

"The circuit's gripped-up quite a bit, although obviously it's rained now, which is not so good," said the 2009 world champion.

"I like the fast section - I like every part of the circuit until you get to the stadium.

"It's like doing the Race of Champions in there, it's so tight.

"You can't really unleash the positives of a Formula 1 car.

"I'm sure it's nice for the fans in the stadium, but to drive it's not an enjoyable part.

"But I like the rest of the circuit. Now there's a bit of grip, it's fine."