@BalazsLengyel: We get a huge amount of comments and we are trying to work through as many as possible. The track temps make a big difference to the tyres. The compounds are designed to work in track temperatures around 30-40C and we're struggling to get much above 15-20C this week. It depends on the tyre - the soft works better in lower temps than the mediums for one lap - and Pirelli has a winter compound which is designed to allow longer runs in lower temps.
We've just hit midday and it's a 2014 car leading a pack of 2015 cars - proof headline times are not always that reflective of what's really going on.
I'll be taking over from Laurence for a while as we approach lunch at the circuit, which starts at 1300 local time.
Good to see Palmer getting some mileage under his belt. The Lotus driver has just crossed for his 25th lap of the day so far.
@CrM: That's not completely clear. It's likely they are running a 2014 engine with some modified parts from this year's engine, so there will be benefits from testing. From what we hear in the paddock its unclear exactly which teams are running what - for example, I heard Toro Rosso may well have run a 2014 Renault engine in Jerez.
@TheGhoul: Doesn't look it!
It would be nice for a team like McLaren to make a drastic change like that every now and then. As Red Bull's camo livery proved, fans enjoy something a little different.
@RRicherdsonMelchi: It can be anything, lower fuel loads and different tyres to the rest the most likely explanation.
Alonso has posted two near-identical times in the low 1:27 range. He's ticked over onto his 25th lap.
@KavinVora: No problems the team have confirmed. These sessions are not just about headline times though, he's accumulated a handy 28 laps already and there's still nearly six hours of track time left today.
@Fascinator: Williams was fastest through the speedtrap yesterday.
@LeeJellyman: There may be more reasons, but I would wager sponsors who pay for a spot on those areas of the car prefer white on black because it's the easiest to see. The Rexona branding on Williams' front wing is a good example.
@Matt: Haha. Maybe change the end of that to 'this test' and then I'll agree with you.
Ricciardo leaps into second, posting a 1:25.274, a time set on the yellow-striped soft tyre.
@Heman: The minimum weight has actually gone up this year from last year, from 691kg to 702kg. This means there is less pressure on drivers to shred their weight as there was last year, and also less of a hindrance for the taller drivers out there.
@metrictoaster: It is mandated in the regulations that teams can't just run their main drivers at tests this years. At least two of the four in-season test days must be allocated to 'young drivers', defined as someone who has not competed at two races or less. It's a good opportunity for the likes of Jolyon Palmer and Pascal Wehrlein to get F1 track time at a time when full-time opportunities are at a premium (in every sense of the word).
Ricciardo is lapping quicker and quicker and he has gone fastest, posting a 1:24.574. Raikkonen moves into second behind him.
Just spent five minutes watching cars bombing down the main straight. Much more sparks this year than last year. Perez's headline time was set on super-soft tyres, I should point out.
Rosberg is getting another hefty stint under his belt on medium tyres, which is why he's not really bothering headline times.
We're just 15 minutes away from lunch in Barcelona. Siesta anyone?
The Renault engine definitely doesn't sound 100% as it should, or as you would expect it to. I can't quite put my finger on it but it's as if it's missing a step somewhere every time it comes flying past us on the pit straight.
Personally I'm very surprised. Unpopular and French are never two words I usually associate with one another.
A couple of minutes to go until lunch now and we have Raikkonen, Rosberg, Massa and Sainz getting a few final laps under their belts.