The post-qualifying car weights ahead of this weekend's Turkish Grand Prix - as published by the FIA - have once more thrown some light upon who is genuinely on the pace and who has conversely been flattered somewhat by their grid position...and on which of the two Red Bull Racing drivers was actually the quicker.

Sebastian Vettel may have stormed to his second pole position of the 2009 Formula 1 World Championship campaign around the undulating, technically challenging and physically demanding Istanbul Park Circuit, but in order to do so he ran lighter than all of his immediate rivals in terms of fuel load, meaning he will have to pit the first of them during the race too.

Just a tenth of a second ahead of Brawn GP adversary Jenson Button at the close, it transpires the young German was running some 6kg lighter than the Briton in Q3 - making former Red Bull ace David Coulthard's suggestion that the pole-sitter would perhaps stop just a lap or two sooner than the current world championship leader look a touch optimistic.

Rubens Barrichello in third, by contrast, is lighter than Button, but the man to watch on race day could be Vettel's team-mate Mark Webber, less than three tenths adrift in the final reckoning but with the heaviest car of any of the top five on the grid - 6.5kg heavier than the sister RB5.

Jarno Trulli's drop-off in form in Q3 was reckoned to have been the product of a cautious strategy from Toyota, but that was belied when it was revealed that the Italian's car is in fact the third-lightest inside the top ten, behind only Vettel and Fernando Alonso, whose grid position of just eighth place given the comparative lack of fuel in his Renault only serves to underline exactly how much the former double world champions are struggling this year.

There was little joy, either, for Istanbul 'record man' Felipe Massa, who despite running some 4kg lighter than Ferrari team-mate Kimi Raikkonen, was pipped to sixth spot by the Finn by just over four hundredths of a second, making the Brazilian's chances of adding a fourth successive victory to his impressive Turkish Grand Prix laurels on Sunday appear unlikely indeed...

The full list is as follows (their actual starting position is in brackets at the end):

Fernando Alonso Renault 644.5kg (8th)Sebastian Vettel Red Bull Racing-Renault 649.5kg (1st)Jarno Trulli Toyota 652.0kg (5th)Rubens Barrichello Brawn GP-Mercedes 652.5kg(3rd)Felipe Massa Ferrari 654.0kg (7th)Jenson Button Brawn GP-Mercedes 655.5kg (2nd)Mark Webber Red Bull Racing-Renault 656.0kg (4th)Kimi Raikkonen Ferrari 658.0kg (6th)Nico Rosberg Williams-Toyota 660.0kg(9th)Robert Kubica BMW-Sauber 664.0kg (10th)Heikki Kovalainen McLaren-Mercedes 665.0kg (14th)Adrian Sutil Force India-Ferrari 668.5kg(15th)Kazuki Nakajima Williams-Toyota 680.4kg (12th)Nick Heidfeld BMW-Sauber 681.5kg (11th)S?bastien Buemi Scuderia Toro Rosso-Ferrari 686.5kg (18th)Giancarlo Fisichella Force India-Ferrari 688.5kg (19th)Timo Glock Toyota 689.0kg (13th)Nelsinho Piquet Renault 689.6kg (17th)Lewis Hamilton McLaren-Mercedes 696.5kg (16th)S?bastien Bourdais Scuderia Toro Rosso-Ferrari 701.0kg (20th)