Fernando Alonso set the fastest time of the day - and the second best by a 2012 car across all four days - as Ferrari ended the pre-season test at Jerez on a positive note.

The Scuderia had struggled to get on top of the radical F2012 during the first three days but, with Alonso at the helm, it rose to the top of the timesheets early on in day four and was never displaced.

Alonso ended with a best of one minute 18.877 seconds, set at the start of a six-lap run which also included laps in the 1:19 and 1:20. It was enough to put him seven tenths clear of the day four field, with only Romain Grosjean on the previous day able to go faster in this year's new breed of cars.

Alonso was, however, only able to set two timed laps after 11.00 local time as Ferrari grappled with a hydraulic issue that restricted its afternoon programme - yet the Spaniard was confident that Ferrari would be in better shape at the next test in Barcelona.

"I still think there is a long way to go until Australia, in terms of how many days and how many tests we can do," he said.

"The progress in these four days has been quite big for us. Maybe not in performance or times or whatever, as I don't know what the times were like in the first two days or what were the track conditions in the first two days compared to now, but definitely all the tests we did and all the understanding of the car has been positive for us.

"We will arrive to Barcelona much more prepared than how we arrived in Jerez... Day one in Barcelona will be a much better starting point."

Jean-Eric Vergne hung on to second despite a late rally from Sebastian Vettel in the RB8, which had been beset by electrical issues in the morning.

Vergne finished his second day for Toro Rosso with a 1:19.597, nine thousandths quicker than Vettel's benchmark, set in the afternoon when conditions were not at their prime.

"When you have a good car, and a good balance, you can tell - and it looks quite good to me," the Frenchman said following his first day of running at Jerez. "I am a rookie, but I drove the best car in the world I think last year.

"Obviously it was on one track and with really good temperature and conditions so it makes it hard to compare, but I have a good feeling. From the very first lap the car was well balanced, and I'm confident we have a good base."

Lewis Hamilton finished fourth, just 34 thousandths of a second down the road in McLaren's MP4-27.

Romain Grosjean did not get down to his day three benchmark, but did enough to end the day in fifth with a 1:19.729.

Sauber's Kamui Kobayashi, taking over from Sergio Perez for the final day, sealed sixth with a 1:19.834. A hydraulic leak on the C31 brought about one of several short red flag periods, although the team was able to repair the car and return to the track before the day's end.

Nico Hulkenberg, Bruno Senna and Jarno Trulli rounded out the day's running order.

Hulkenberg, getting his first taste of the new Force India after a planned run on Thursday afternoon was scuppered by Jules Bianchi's crash, completed 90 laps and was the last driver to break the 1:20 barrier.

Senna managed an impressive 124 laps on his way to eighth fastest. The Brazilian's day included 25 and 37-lap stints, and also featured a stoppage on track from which he and the car were quickly recovered.

Trulli, the day's other newcomer over at Caterham, completed 117 laps and finished with a best of 1:22.198, just over three seconds down on Alonso.

Friday' test times:

(Pos-Driver-Team-Time-Laps)

1. Alonso Ferrari 1:18.877 39

2. Vergne Toro Rosso 1:19.597 +0.720 80

3. Vettel Red Bull 1:19.606 +0.729 50

4. Hamilton McLaren 1:19.640 +0.763 86

5. Grosjean Lotus 1:19.729 +0.852 95

6. Kobayashi Sauber 1:19.834 +0.957 76

7. Hulkenberg Force India 1:19.977 +1.100 90

8. Senna Williams 1:20.132 +1.255 125

9. Trulli Caterham 1:22.198 +3.321 117

AutoSport