@robert: Button is expected to be back in the car for the final day tomorrow.
@Smurfer: They definitely still have a power advantage, but the best answer is a combination of the factors you mentioned. And don't forget that one affects the other. Engine manufacturers could get more power out of the PUs with more cooling, but that would be at the detriment of the aerodynamics. It's one big package and Mercedes' is the best.
@mike: The engine manufacturers can test on dynos back at their factories to try to simulate the stresses a PU goes under. I'm not sure exactly how the FIA monitors wind tunnel time, but each team has to demonstrate that it has only used either 30 hours in the wind tunnel or 30 teraflop of CFD data or a combination of both.
@JanVisser: 66 tokens would represent changing every one of the listed components in the engine. In fact the existing manufacturers (Ferrari, Mercedes and Renault) have 32 tokens to spend, but that is still a huge amount. They can spend them at any point during the season, but it looks like Renault and Mercedes are keen to speed the majority of theirs before the start of the season. The PU has to be homologated before the start of the season, but unlike previous years, further performance tokens can be spent later in the season if a manufacturer desires. Honda is the odd one out as it's new to the sport, so it has to homologate its PU on March 2. Up until that point it can work on any facet of the PU to improve performance. It will also be given tokens to spend based on an average of how many the others have left. So, let's say Mercedes spends 22, Renault 17 and Ferrari 12 (just an example) then Merc would have 10 left, Renault 15 and Ferrari 20. Honda, as a result, would get 15 to spend as that is an average of the others.
@ankur: Red Bull admitted it probably spent too much time on the 2013 car at the end of that year and not enough on the 2014 car, but to be fair to them the RB10 was a good chassis and aero package let down by the Renault PU. Of course, it's a team game, but Renault was still trying to be relatively equal among its customers and Red Bull suffered as a result. Renault also were no way near as ambitious as Mercedes and less prepared - they simply did a worse job. However, Mercedes benefited from the KERS research it had done with McLaren when the two were a works team back in 2009 and Renault was a bit behind in this respect after using Magneti-Marelli as its supplier of KERS during that time. But that's not to take away from the guys at Brixworth, who also did very well to conceive and reliably build its split turbo design as well as building a huge amount on the solid foundations it had with McLaren's KERS.
@McNeilNtandoMdluli: I agree Aldo Costa is a bit of unsung hero at Mercedes. Along with Bob Bell and Geoff Willis, he produced one of the most impressive cars of the last 20-30 years in the W05. Allison has only ever worked with limited resources before Ferrari and did a very good job with the Lotus E20 and E21.
@James: Sorry, that's per week and the limit was brought in at the end of 2013, significantly reducing the time teams could spend in the wind tunnel.
@Vers: Give it time. Remember this is the just the second day that car has run. The fact it has 38 laps so far this morning and 77 from yesterday is impressive.
@Timmo: That's the plan at most of the teams. But you have to remember there are no points in testing, so the qualifying sims are as much about procedures as setting fast times. It still won't give us concrete proof of who is fastest.
@TravisUSA: HRT completed just 10 laps at a filming day before the 2012 season (it's last in F1). I was at the final test in Barcelona that year and the team had the car in the garage but couldn't get it running. It failed to qualify at the first race.
@huey: Yep, once an engine is used it won't be allowed to benefit from future upgrades. So let's say a team brings some upgrades ahead of the introduction of its fourth engine, then only the fourth will benefit. However, if that fourth engine blows up then they will have to go back to using one of the earlier engines, which will be detuned in comparison.
@MikeInDenmark: The manufacturers make all of the components as far as I'm aware, but the installation may be different on each.
@DreamHonda: As far as we know, they are working on more mileage which is the most useful for them at the moment.
Good news for Force India fans, Hulkenberg has improved to fifth fastest with a 1:27.404 on the medium tyres. Still a long way to go, but progress is taken in small steps at this stage of a car's development.
@asdf: First off, the air is going through the wheel and not the tyres. But the best way to think about it is two channels for the air - one for the cooling the brakes as per usual and one for the blown wheel nut. It's why the brake ducts on cars with blown wheel nuts are so much bigger than the ones without.
@Brad: Interesting stuff from James Allen and tends to correlate with our own conclusions. There are two number of factors in top speed times - power and drag. It all depends on what the teams are testing as to what settings they will use. I think Mercedes aero package was probably under-rated last year as everyone praised the PU. But you have to remember it is a joint effort. Some aero gains may be sacrificed for cooling purposes and this year the key has been getting more power from the PUs with less cooling. That has a huge impact on drag, so isolating PU and aero is not that useful, I think.
@Rishi: ICU? Anyway, I can inform you that Honda does make the ERS but has also benefited from McLaren's know-how in that area. But ERS units are manufactured in Japan - we don't need another McLaren conspiracy story doing the rounds.
@BogdanKrstic: Just updated the times and in the last 45 minutes McLaren has added another 13 laps, so no major issues right now with Magnussen currently on track.
@Ethanpayne: Soft tyres for that time. But it looks like quite a long run so he must have a respectable amount of fuel on board.
@Brad: Mercedes has made some pretty big steps with it's aero package. A lot of people are saying it's the same, but it's quite clearly not. An evolution, sure, but plenty of work has gone on at Mercedes over the winter, make no mistake. Downforce levels are very difficult to calculate, as I mentioned in the previous post it's a drag v downforce trade off along with cooling requirements for the PU, gearbox etc. I wouldn't get too hung up on who has the most downforce as you will never be able to say for sure without access to the wind tunnels. The overall package is what matters and that is measured by lap time.