Caterham convinced upgrade package is paying off after British Grand Prix practice

The Russian admitted that wet conditions in Silverstone practice made it difficult to judge the outright performance gain, but was certain that the overall downforce level of the car has been increased.

The new package includes modified exhausts and sidepods, with a new radiator exit, as well as a new engine cover and tweaks to both the floor and the front wing.

"The weather disturbed our plan a little bit because we had a lot of parts to try, but we can definitely see a big improvement from the package," said Petrov when asked by AUTOSPORT for his impression of the updates.

"You can feel that there is much more downforce and now we need to change the car a bit to suit this configuration."

Petrov, who ran with the car in its previous specification in the morning session to allow a comparison with the updated sister car of Heikki Kovalainen but switched in the afternoon, is hopeful that there will be dry running on Saturday morning to allow the team to gather definitive data.

"Today we were careful and we didn't want to push to the maximum, but tomorrow from P3 we will push as much as we can and see what this configuration has given to us," he said.

"It's important to have a dry day because you need to [see where you are compared to] the teams in front.

"In the rain, it's very difficult to compare. Heikki was P8 so let's see what happens tomorrow. [Toro Rosso driver Daniel] Ricciardo was in the top five in P1, so you never know. In the dry, it's easier to see."

Petrov added that it was "definite" that the team would continue to run the cars in updated specification for the rest of the weekend.