Watched by King Juan Carlos, and to a deafening roar from his ecstatic compatriots decked out in Renault's blue and yellow colours, the 24-year-old ended Michael Schumacher's [ Images ] hopes of a third win in succession for Ferrari [ Images ]. The German, six times a winner at the Circuit de Catalunya and Alonso's closest rival in the championship after winning his home grand prix at the Nuerburgring last weekend, finished second 18.5 seconds adrift.
Alonso said winning in Spain was the best feeling he had had in a racing car since he clinched the championship in Brazil [ Images ] last year.
He added: "It was a maximum performance from the car, the tyres performed really well throughout the race.
"We needed the gap (to get past Schumacher's Ferrari) and we found it fairly quickly. It was a defending race from there on." he told ITV Sport.
Alonso's third win of the season, and 11th of his career, extended his overall lead over the seven times champion to 15 points after six rounds. The Spaniard has now also finished the last 12 races on the podium.
After a strategic race short on incident, Alonso has 54 points to Schumacher's 39.
Italian Giancarlo Fisichella [ Images ] completed a solid afternoon for Renault, who announced a long-term commitment to Formula One before the race after carmakers agreed to sign a new commercial deal to 2012, by taking third place. Brazilian Felipe Massa [ Images ] was fourth for Ferrari, ahead of McLaren's [ Images ] Kimi Raikkonen [ Images ] and Honda's Briton Jenson Button [ Images ] and Brazilian Rubens Barrichello [ Images ]. Germany's [ Images ] Nick Heidfeld [ Images ] pocketed the final point in eighth place for BMW Sauber [ Images ].
"We needed the gap (to get past Schumacher's Ferrari) and we found it fairly quickly. It was a defending race from there on.
Raikkonen's team mate Juan Pablo Montoya [ Images ] had a miserable afternoon, spinning on the 19th of the 66 laps and retiring.
"I don't know what happened. It's hard to understand what's going on...My start was dreadful again," he told Britain's ITV television.
"We're trying to improve the car, you know. We ran some fuel here that we never ran before. The car was very heavy."
The German had to pit to replace a damaged front wing while Trulli, still without a point this year, finished 10th.
"We were not racing each other, I just tried to overtake him...we were good in qualifying but not good enough in the race," said Ralf.
Briton David Coulthard [ Images ] finished out of the points in his 200th grand prix after starting from the back row of the grid in his Red Bull.
1. Renault 78
2. Ferrari 59
3. McLaren - Mercedes [ Images ] 42
4. Honda 24
5. BMW Sauber 12
6. Williams - Cosworth 10
7. Toyota 7
8. RedBull - Ferrari 2
9. Toro Rosso - Cosworth 0
10. MF1 - Toyota 0
11. Super Aguri - Honda 0