Scuderia Toro Rosso's Sebastian Vettel heads the pack on day 1 of the Jerez test in Spain - the final test prior to the summer testing ban.

Sebastian Vettel set the pace at the Jerez de la Frontera circuit in the extreme south of Spain on Tuesday where drivers' and teams' had to cope with track temperature exceeding the 50 degrees Celsius mark.

Vettel, who set the fastest time of the day in the morning when it was cooler - a 1 minute 19.844 seconds - completed 94 laps in total, getting through his entire programme without any technical glitches.

Aero testing followed by mechanical work aimed at improving set-up and traction were the first items on the agenda for the German, before he evaluated some new brake materials and then switched back to aero work.

He will now continue running on Wednesday, when he will spend the entire day working on Bridgestone's new 2009 spec slick tyres. Bridgestone has opted to take the medium compound dry grooved Potenza tyres as well as two compounds of 2009 tyres to this test, as prepations for next year.

Gary Paffett was 'best of the rest' meanwhile for McLaren-Mercedes, the Englishman coming in around two-three tenths slower on a 1m 20.179s. He did 80 tours and fine-tuned a wide number of aero components, as well as looking at different suspension set-ups.

Luca Badoer was third and the Scuderia will be keen to try and make some significant progress this week ahead of the Hungarian GP, after less than sparkly runs in Britain and Germany.

Badoer worked on two main areas - the morning was dedicated to comparing various different aerodynamic solutions, while in the afternoon, he ran slick tyres in preparation for the 2009 season, with the consequent modifications to the aerodynamics on the F2008, to try and replicate the levels of downforce that will be required starting next year.

"We completed our planned programme," said Badoer, who did 69 laps in total, his best effort coming towards the end of the day.

"This morning it was important to go deeply into some technical elements to understand what happened last Sunday in Hockenheim. We picked up a lot of data, and that will continue over the next few days when we also test some solutions for the forthcoming races."

Williams' tester Nico Hulkenberg was fourth as the Grove-based operation looks towards Budapest and what is the eleventh round in the 2008 FIA Formula 1 World Championship.

"Nico Hulkenberg drove the car today and concentrated on general set-ups," explained Williams test team manager, Dickie Stanford. "Our running was cut short by a technical problem later on in the afternoon, but we fortunately didn't lose too much time. Nico Rosberg joins us tomorrow for day two."

Further down the order Sebastien Buemi was fifth for Red Bull, just four hundredths slower in his RB4. He had a good day and completed his entire programme, working mainly on suspension, as well as carrying out other development work, both short and long term. He also did 110 laps - the most of anyone runner - and 39 more than Romain Grosjean, who was next up in the works powered Renault.

"It was my first time here in Jerez and so I had to learn the track this morning and worked gradually with the team improving the car throughout the day. It still feels amazing to drive this car and I was glad to have the chance to work with the team again," said Grosjean.

"It was quite difficult today because of the high temperatures, but I really enjoyed driving this circuit with the mix of high and low speed corners. I'm now really, really looking forward to observing the team for the next couple of days to learn as much as I can."

"It was the second day of running we have done with Romain and he did a good job on a circuit that was new to him," added Renault's chief test engineer, Christian Silk. "We concentrated on getting him comfortable with the car and he coped well with the difficult track conditions caused by the heat, which made the balance of the car quite tricky.

"Running in the heat may have been difficult, but some of the races coming up, such as Hungary, are traditionally very hot and some of the things we have learned today will be relevant for those races."

Of the rest Jarno Trulli was seventh, a tenth or so up on the Honda of Alexander Wurz. Trulli spent the day on Bridgestone's new slick tyres as part of the team's early preparations for 2009. Running with a low-downforce package, he had a trouble-free day and completed nearly 100 laps.

"After a string of races and tests with mixed weather, it feels really hot here at Jerez. Today we have been concentrating on the new Bridgestone slick tyres for 2009. For that reason we have run with lower downforce to simulate the aerodynamics package that we will have next season. We have made a good start and collected some interesting data for the development of next year's car," he reflected. "Tomorrow I will begin work to prepare for Hungary."

"Apart from two installation laps, we spent the whole day working on the new tyres for 2009," added Toyota's test team manager, Gerd Pfeiffer. "It is the third time that we've tried them but we completed very little mileage on either of our previous attempts. So this was our first full day of running and we spent our time looking at different set-ups.

"The car ran without problems despite the extreme heat and we gathered a lot of information that will help us with our plans for next season."

Honda's focus was slightly different, as team boss Ross Brawn revealed on Sunday following the event at Hockenheim: "We have a four-day test in Jerez this week when we will be evaluating our new rear suspension, which we are optimistic about. We also have the latest update to our aero package, so I think those two elements combined should enable us to make a step forward in Hungary," he predicted prior to the start of today's running.

The only other runner to venture out was BMW Sauber's Christian Klien, however, he only did 3 laps and did not set a time after one of his mechanics suffered an electric shock due to a problem with the new Kinetic Energy Recovery System. For more details see separate story click here. BMW now hope to resume running on day 2.

The four-day Jerez test now continues on Wednesday, with Ferrari, McLaren, Williams, Renault and Red Bull Racing bringing in Kimi Raikkonen, Pedro de la Rosa, Nico Rosberg, Nelson Piquet and Mark Webber respectively. Jarno Trulli, Sebastian Vettel and Christian Klien will all run for a second day. Force India will join proceedings on day 2 too, where it will test its new quick shift gearbox.

To see the testing times from day 1 click here.