Sauber was the team with the biggest update package as F1′s ultra-rare in-season test began on Tuesday.

Kamui Kobayashi was in charge of the revised C31, which including a new exhaust and front wing represented “the biggest update package” of all the teams at Mugello, according to Germany’s Auto Motor und Sport.

McLaren, in contrast, have taken “no great updates” to Tuscany, which explains why Lewis Hamilton and Jenson Button have left the task up to the British team’s test drivers.

It was a similar story in the Mercedes camp.

Williams’ Valtteri Bottas, however, was in charge of testing a new McLaren-like exhaust for the FW34, while Ferrari also has a new exhaust for the F2012.

On Thursday, as the three-day test wraps up, the famous Italian team will debut other developments, including a new engine cover and sidepods.

A new front wing, nose and floor will only be ready for Barcelona.

There were no radical modifications on display by Red Bull, who instead want to use the Mugello test to work on car setup.

“We still need to learn how to get the most from what we have,” confirmed Bahrain winner Sebastian Vettel.

For that purpose, the Ferrari-owned Mugello circuit might not actually be the best venue.

“It’s great for driving,” said Mercedes’ Nico Rosberg, “but for the engineers Barcelona would be a bit better because there are all types of corners.

“At Mugello they are mainly fast, and virtually none at low speed.”

Williams will try a developed version of its F-duct system at the Valencia street circuit this weekend.

The British team’s interpretation of the McLaren-like concept first appeared in China, but technical boss Sam Michael said then that he expected it to take “a couple of months” to perfect.

Very little about Williams’ F-duct – called the ‘blown rear wing’ by the Grove based team – has been heard since.

But on Monday, the team announced that the innovation will feature on the FW32 alongside some other new parts at the European grand prix.

Williams, however, referred in the media statement to its Valencia-spec F-duct as “the development blown rear wing”, indicating that the component may not be fitted for qualifying or the grand prix.

“We’ll have more new parts for this race but we’ll have to wait and see what improvements they bring to the car,” said driver Nico Hulkenberg, whose teammate Rubens Barrichello won at Valencia in 2009 at the wheel of a Brawn.

Hulkenberg added: “We are inching a bit closer to the top ten, as we showed in qualifying in Montreal, but we have to continue pushing and gain more tenths to get into the top ten consistently.”

(GMM)