Formula One's Norfolk-backed constructors Caterham and Lotus can head into the new season with optimism as the final winter test came to an end on Sunday.

Enstone's Lotus finished the four-day preparation in Barcelona as they started it – topping the time sheets thanks to another impressive run from former world champion Kimi R�ikk�nen, who produced a best lap of one minute 22.030 seconds before lunch.

The Finn also topped the day's lap charts with 121 to his name, as most of the grid settled on slower race simulations during the afternoon.

R�ikk�nen finished two tenths ahead of Fernando Alonso's Ferrari – although the word from Maranello is podiums may be out of the team's reach in the opening races, starting from the first grand prix in Melbourne on March 18.

'Of course, the fastest time at the end of the day looks good but no one will know how fast any of the cars are until we get to qualifying at Albert Park,' said R�ikk�nen. 'All the changes we have made over testing have been improving the car, so we'll have to see what happens in Melbourne in a couple of weeks' time. I'm feeling positive.'

Bruno Senna's Williams also showed good pace, but world champion Sebastian Vettel suffered reliability problems and a wander off track as his final day of testing saw his Red Bull slowest on the time sheets and clocking just 23 laps.

As for Hingham-backed Caterham, Vitaly Petrov completed 101 laps for the Norfolk outfit with a best of 1:22.765 – three tenths behind the McLaren of Lewis Hamilton – despite a late excursion off track.

'The team has done a fantastic job all day and we've been improving in every area each time we went out,' said Petrov. 'I had my new seat today so I'm really starting to get comfortable in the car and the lap times are coming down, the set-up is improving and everything is working really well.

'The last lap before lunch was close to perfect for me, with the conditions and the way the car behaved, but we know there is still more to come so that is good news, it keeps us pushing.

'This afternoon we were looking at a race simulation and despite the slightly early end to the day it all went to plan. The degradation levels were manageable and we didn't have any issues at all with any of the systems – Kers, engine, gearbox or anything mechanical.

'We do have work to do, that's the same for everyone, but I think we have prepared as well as we can for Melbourne so for me this has been a really good first couple of weeks with the team.'