@James: If you've ever seen Hamilton's tweets you'll know where I'm coming from.
@James: I think so. Mercedes has one of (if not the) most marketable athletes in the world. And he happens to be one of the best drivers in a generation too. It's money well spent from that perspective.
@Leo: The paint is designed to dry at high speeds, so teams can put it on their cars, run for a few laps and then come back and see how air is flowing around the car. Much like the aero sensors we saw earlier, it's all part of the essential data gathering process at this stage.
Not a lot to report on from the track itself. Rosberg returns to the pits after what I assume was a higher fuel run on mediums.
@whatishappeningwith...: We don't know fuel loads at this stage. I would gamble Ferrari was doing a slightly higher fuel run than the others.
I will now hand over to the very capable hands of Laurence Edmondson. Be gentle with him.
Good morning all. Verstappen, Button and Vettel are currently on track. Good to see the McLaren back out and already well past yesterday's lap count.
@rockedin123: There's little doubt that the Ferrari will be considerably quicker than Sauber this year, but yesterday's time by Ericsson was set on super-soft tyres - so it's a bit misleading. Ferrari have more updates coming for these final three days, but don't be surprised to see slowish lap times as they run aero tests.
@James: Although you can't always compare like-for-like in testing, trends do start to appear at this stage. Mercedes is definitely quick and that's no surprise, but Williams has shown some positive signs and Ferrari and Red Bull have big updates due this week.
@James: Mercedes was running very similar front and rear wings at Jerez to last year but has since updated the rear wing significantly. Yet to see if they have their new front wing here this week, but there will definitely be an update of some sort in that area before Melbourne. It's fair to say that much of the aero package is an evolution - it now has even more extreme versions of its novel lower front wishbones - but after such a successful year in 2014 it would make no sense to go radical.
@Hole_in_One: Mercedes learned a lot in 2012 and 2013 and were able to use that knowledge to influence the 2014 car, which as you point out, was very different to its predecessors.
Rosberg has the whole track to himself at the moment. 35 laps completed in the Mercedes as he continues to run on medium tyres.
@formulax1: The team was owned by tobacco company BAT, so it was promoting its own brands - much like Force India and Red Bull do now.
@MelhemSake: Constant speed is what they are aiming for so they usually run slower than full speed and don't push in the corners too much. But I've never seen one come off.
The Benetton ran with coloured sidewalls on the Pirelli tyres as a special one off at Detroit that year - sadly we don't have a pic in our archive.
@IanF: Red Bull is running aero tests with a big rig on the car this morning (see pic below) so Kvyat hasn't completed an entire lap yet.
@MelhemSake: Button has just gone back out and now they are up to 25! Not great by the standards of its rivals, but progress is progress.
@StevenWilson: Clearly negotiations are getting spicy. You always have to ask who is putting pressure on who when these figures are quoted in the papers. Considering Hamilton's ability behind the wheel and growing celebrity outside F1, he is worth an awful lot to Mercedes. However, there is no doubt that he wants to stay at Merc because he knows that offers him his best chance of more titles.