Mark Webber admits that perhaps the biggest regret of his F1 career is accepting an offer from the Williams team just as Renault rose to become the sport's dominant force.

Having impressed with both Minardi and Jaguar, despite each team's own lack of performance, Webber was in line to move to Enstone for 2005, but spurned the advances of manager Flavio Briatore - who ran the Renault operation - to take up a similar offer from Williams, on the basis that the Grove squad was already successful.

"[The only thing I would change] "would be to have gone to Renault rather than Williams [in 2005]," he told Britain's Guardian newspaper as he reflected on his career with six races left to run before retirement.

"Renault hadn't won a race but, soon after that, they ran [F1]. They were like the Red Bull of the time. I would've been winning earlier and had Fernando [Alonso] as a team-mate. [Instead] I had to rebuild myself and that took a bit of juice out of me."

Coming from the backwoods of Queensland, Webber rarely allowed himself to envisage a future in the top flight, but that didn't prevent him from working hard at making the dream a reality. Having battled his way up through the ranks, moving to Britain to contest FFord and F3 before sportscars and F3000 came calling, the Australian did not have the sort of 'development programme' opportunity open to young talent these days, but insists that they don't always produce the right drivers for F1.

"I started late, although 24 is probably the right age," he noted, "Look at [Nigel] Mansell and [Mika] Hakkinen - those guys didn't start until then. That was normal. You didn't get near a top car. Now, with simulators, the kids are coming in so fast. We've got so many guys on the grid who probably shouldn't be there."

Sebastian Vettel, the driver with whom Webber's career has been most closely linked in recent years, is among those to have come through the ranks on the back of such a scheme and, while the Australian does not dispute his rival's place at the F1 table, he admits that relations are far from cordial.

"I suppose some of the private discussions that Sebastian and I have had since [Malaysia] have been a bit disappointing," Webber said, "Forget the track stuff. We've had some private discussions and we weren't super-happy with how they went and how we felt about each other. It's tested the relationship to the maximum, [so] we're just going through the professional situation because you've got a lot of people busting their balls for you - the guys working on the car."

Admitting that he already knew that 2013 would be his last season in F1 before the opening race in Australia, Webber revealed that he had told Red Bull owner Dietrich Mateschitz of his decision, but had left it to the Austrian to handle the information as he felt fit. Team boss Christian Horner clearly hadn't been informed when the news officially broke ahead of the British Grand Prix....

"My communication with Dietrich was always open and very strong," Webber noted, "That was important. We'd always had a good relationship and I told him I wanted to stop even if he said there was always a seat for me. Once he'd been informed, then it was good for me and Porsche to get the announcement out nice and cleanly."

Whilst looking forward to the new challenge of leading Porsche's nascent sports prototype programme, Webber also wants to bow out on F1 on a high, even if his motivation for life in the top flight has faded slightly in the past few years.

"I'll miss driving the car and being out there on your own, racing, but the decision is made and, mate, it's the right decision," he concluded.