Alonso gets behind the wheel of a McLaren for the first time

Renault agreed to let Alonso, who is under contract until the new year, familiarise himself with his new car.

The 25-year-old Spaniard wore unbranded overalls as he tested in an unmarked car at Jerez in Spain.

Alonso, who thanked Renault for the chance to drive the McLaren, was 0.250secs slower than his new English team-mate Lewis Hamilton.

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Alonso said in a statement released by McLaren: "I'm pleased that I was able to drive the McLaren-Mercedes Formula 1 car earlier than expected and would like to thank Renault and Flavio Briatore for agreeing to this.

"I'm really excited about the future and would like to wish everybody a merry Christmas and a happy new year."

Briatore, the Renault F1 team boss, said: "Considering his fabulous achievements these past two years we decided to give him this opportunity."

Indy Racing League star Marco Andretti, son of former McLaren driver Michael and grandson of 1978 world champion Mario, had his first taste of an F1 car thanks to Honda.

The 19-year-old American was two seconds off the pace of Honda test driver James Rossiter.

Another star from American racing, triple Champ Car champion Sebastien Bourdais, completed his three-day test with Toro Rosso.