Welcome back to ESPNF1's live commentary of the Abu Dhabi Grand Prix. Next up is second practice and hopefully a clearer picture of how the teams are stacking up against each other at Yas Marina this weekend.

The McLarens were fastest in FP1 with Lewis Hamilton leading this man Jenson Button by 0.333s ...

© Press Association

It could be a very interesting weekend if the McLarens can challenge Red Bull in qualifying and Ferrari takes them both on in the race.

Shantanu asks: "I would like to know what is curfew exceptions at an F1 race? According to reports, Ferrari used one of its four curfew exceptions on Friday morning as mechanics arrived at the track early ahead of opening practice for the 2012 Abu Dhabi Grand Prix. Please elaborate on this."

To avoid mechanics working silly hours the FIA imposes a curfew to ensure they are not working through the night. On four occasions per season a team can break that curfew without penalty and Ferrari opted to do that on Friday morning to get the cars ready with all the new updates. The cars came straight from India and the updates have been flown in from Maranello, so the team needed a little extra time to get the car ready.

McLaren has a few updates of its own this weekend. Here's what technical director Paddy Lowe had to say about the first practice session: "It went quite well, a good start, both drivers pretty happy with the car; we had to make a few set-up changes just to get it a little bit better with the balance. The caveat of the whole session is that's not representative condition of qualifying and the race which will be in the evening, so we'll see how it'll be in P2."

Lowe puts the times down to "The normal Friday mystery, we just go out and do our own thing and see where we are. We're not misplacing that confidence; it will be P2 that tells more of a story - as much as Friday ever does - of where we're going to be tomorrow and Sunday"

Madhan asks: "How RBR has so high downforce and how exactly downforce helps the car performance? It is related to the wings or body of the car?"

Downforce helps performance by pushing the car into the track and giving the driver more grip. A good Formula One car has every aerodynamic surface working in unison with all the others, so it's always hard to pinpoint one factor for a fast car. However, Red Bull has put a lot of development into its exhaust and using its gases to seal the under the car to enhance the performance of its diffuser. It has also brought an improved drag reduction system to recent races, which helps the drivers in qualifying where DRS use is unrestricted.

Just to set the scene at Yas Marina, the sun is starting to set and the flood lights are taking over the responsibility of illuminating the circuit. By the end of the 90 minutes it will be night time. A knock-on effect of the sun setting is lower track temperatures and this practice session is particularly important as it is the only one at the same time of day as qualifying and the race.

Sauber is very keen to get going this evening with Perez and Kobayashi queued at the end of the pit lane and ready to go when the green light came on.

Vettel, Webber and Button are all on track. Medium tyres are the compound of choice for the start of this session but the drivers will head out on the softs in this session.

Rahulan asks: "Plenty of times drivers complain that missing out on FP1 has cost them in the races. Can you throw more light on why drivers say that and also why teams opt for a different driver for a single session alone?"

Time in F1 cars is very precious now that in-season testing is limited. If you think of it as a percentage, FP1 is roughly 40% of the practice time available ahead of qualifying, so missing it is quite a big deal as drivers have to get used to the behaviour of the car at the circuit super quick so that they can start working on set-up and tyre comparisons in FP2. For a driver like Senna, who has missed a whole bunch this year, it starts to add up and then people don't take it into account when he misses Q3 by 0.2s in qualifying.

On the other side, the teams use the sessions to give drivers an outing in the car, which the driver usually pays for with sponsorship money. It's the kind of thing they used to do in testing, but no longer can due to the ban.

The times are rolling in already with Vettel fastest on a 1:42.779 and Button second fastest on a 1:42.804.

All the cars apart from Raikkonen and Senna are on track. All the drivers are on hard tyres and Hamilton is about to go fastest...

Hamilton, in fact, just misses out by 0.060s despite setting a blistering pace on the long straights in sector two. The top drivers are already about 0.5s faster than Hamilton in FP1 so Paddy Lowe was right when he said not to read too much into the times.

Adam from down under asks: "Just a quick question about KERS, when drivers deploy it, does it make the engine use a little extra fuel each time they deploy it as it gives more power or is it controlled another way."

Good question and one that I don't know a definite answer for. However, using my basic mechanical knowledge I would say no, as when a driver uses it he will be at full throttle on whatever fuel mix and engine map he is using anyway. The KERS power is stored in a battery, and while the revs will definitely increase when the boost is applied the fuel flow should stay the same. If anybody can enlighten us further please get in touch.

But I would say any fuel use would be negligible and the power to fuel usage ratio would definitely better when KERS is deployed.

Vettel has now return to the pits. Hamilton is still out there but on a slow lap, possibly returning to the pits. The gap between the two is 0.047s, Button is 0.074s off.

Hamilton is told to come back to the pits, but says he wants to stay out. His engineer replies saying if he stays out he will not have time for a setup change on these tyres, but Hamilton is happy with that and remains on track for another lap.

Alonso is currently 0.337s off Vettel, but its the soft tyre laps midway through this session that will be most telling of the true gap between the Red Bull and the Ferrari.

Jonathan says: "Relating to your commentary. During KERS deployment fuel consumption would theoretically decrease."

Not sure about that - the KERS boost adds to the power of the engine rather than substituting for it. But please email your theory through.

Hamilton has now gone fastest as his fuel load comes down. He's set a 1:42.096, which is a whopping 0.635s quicker than Vettel. No wonder he isn't that fussed about a setup change.

Vettel, Button, Alonso, Webber and Massa are all back on track now to try to match Hamilton's lap time.

Harmen on KERS: "As far as i understand the stored energy is used to directly power the drivetrain, and adds to the already available power from regular fuel usage. "

That's pretty much my understanding too.

Paul says: "I would think fuel consumption will be less: more speed/MPH on the same fuel flow per minute."

Ah, I see what you mean - that's talking about fuel over the course of the race, right? I thought the question was about fuel flow at the instant the KERS is deployed. Good question and top answers!

A few more bits of news on the Ferrari updates ... it seems they have new front and rear wings, a new floor and new barge boards.

Amol asks: "Can you explain how do Red Bulls just speed away in first few laps even though we've seen McLarens and Ferraris having better race pace than them...they just fly away and open up a gap of 3-5 secs in 2 laps."

It's a good point and it's crucial to Red Bull's race strategy. The key is that Red Bull know they have an advantage over one lap so they play to that strength by gearing the car and setting up to be as fast as possible in qualifying but also on heavy fuel at the start of the race. If all goes well they build a lead bigger than 1.0s in the first two laps and therefore negate their rivals' use of DRS. Meanwhile, their rivals, knowing they can't match Red Bull for speed in qualifying, have to gear their car for overtaking in the DRS zone and strong race pace. But that strategy falls apart if they are not close enough to pass. It just goes to show that qualifying is still very important and splitting the Red Bulls on the front row will be crucial for Alonso's title chances.

Webber had something flapping from the front of his car's floor, a bit like Vettel had in India. Maybe there's more to that story than we first thought as Red Bull mechanics investigate the car in the garage.

Bob on KERS says: "Engines use more fuel at higher rpms. Using kers adds to the power delivered by the engine allowing the car to go faster and the engine would therefore rev higher using slightly more fuel."

Dimitar asks: "I read very short story about Alonso had been involved with a row with Pat Fry in India. Can you eplain little more about that. Does that Ferrari Family shows signs of break down?"

Ferrari and Alonso say it's nonsense fabricated by the Italian media. I'm inclined to agree with that. Ferrari being slower than Red Bull is nothing new and Alonso doesn't have much to gain by losing his rag with Fry.

Suresh: "Fuel flow at the instant KERS deployed will be Same, extra power from the KERS decreases the load of the engine, and thus the speed increases at higher rate during time KERS deployed, no changes in fuel consumption. I think!"

Anyway, enough about KERS. We'll have a word with an engineer if we get the chance.

Back to the action, and Perez has gone out on the softs. Vergne and Rosberg have joined him on the softer compound. usually drivers set quick laps on their first run on the softs in FP2 followed by long runs for the second half of the session.

Vergne locks up and runs wide at turn 11.

Button and Hamilton are out on softs now. Webber is going out on softs too.

The early laps from Hamilton and Button are not very impressive, it might be taking a while to get the tyres in their operating window.

It looks like a brake problem on Vergne's car as he returns to the pits after running wide.

Webber runs wide in the final corner on his first soft tyre run. The time is nothing special though and he is fifth, 0.722s off the pace.

The Ferraris are now on the softs. Meanwhile, Grosjean has popped up to third fastest on his soft tyres with a 1:42.500

Hamilton is told that other drivers are struggling on the soft tyres too, as he struggles to match his medium tyre lap.

But Vettel has managed to find some extra time on his set and goes fastest with a 1:42.052. Nevertheless, he's only 0.039s faster than Hamilton's medium tyre lap.

Alonso improves to fifth and is now 0.750s off Vettel.

Perez is really struggling to keep the rear of his Sauber in check but he's reasonably quick with the seventh fastest time.

Button has returned to the pits after his first soft tyre run.

More sparks from the front of Webber's floor as he operates DRS down the straights. That car is running very low.

Now Hamilton has found a little extra pace in sector two... he's faster than Vettel heading in to sector three ... but loses time in the final sector and stays second, now 0.168s off Vettel.

Kobayashi has terrible understeer in turn one on his flying lap on soft tyres. Senna does the same.

A Red Bull mechanic is now taking a photo of the floor of Webber's car as the team continues to work on that area of the car.

Mehul says: "I am ardent Ferrari fan but now its really getting frustrating with the development of the car. Why does a company with such automobile history use an obsolete aerodynamics tunnel!! Its ruining Formula One for me and thinking of quitting on Formula One"

I hope you don't quit, Mehul. Ferrari's wind tunnel was opened in 1998 but will have been upgraded since then. Wind tunnels are tricky things to get right and that's why several teams, including Ferrari, use wind tunnels belonging to a third party, such as Toyota. Ferrari is going to upgrade its facility over the winter but to do so it will have to shut it down, which obviously has a cost. In its glory years in the 2000s, Ferrari used to do a lot of testing on track when in-season testing was still allowed, so it was a little behind when that ban came in and they often bang the drum for a return of more in-season testing. It all reminds me of a famous Enzo Ferrari quote: "Aerodynamics is for people who don't know how to build engines"

Back on track, and Petrov has spun off track. No damage done, apart from to his tyres and he gets back on his way.

Vettel remains fastest and has now gone back out on track after a brief spell in the garage. Webber's car now has some electrical tape on its splitter so maybe something has broken on that Red Bull.

Vettel says the information he has received from his engineer is a bit late for the second time today.

Karthikeyan has spun at turn 17. That's a tricky corner where the drivers have to brake and turn at the same time.

So it looks like all the drivers are now on their long runs on the soft tyres. The teams use this stage of the session to simulate the start of the race.

Here's a tweet from Renault Sport, sadly not about KERS, but interesting nonetheless: "Completely dark now, temps are a lot cooler now so the engine has to respond to this new set of parameters"

A lock up for Fernando Alonso into turn eight and he protects his tyres from a flatspot by coming off the brakes and skipping the chicane.

Raikkonen sets a new personal best to go sixth fastest behind Grosjean. Kimi is 0.781s off Vettel at the moment.

Before Webber left the pits on this latest lap some water dripped from the underside of his car. He's still out on track so the team are presumably not that worried.

Ah, no he does return to the pits. It could be a KERS issue to do with cooling. The mechanics are now having a look.

Webber is getting out of his car. This might be the end of his session. Still not sure what the issue is but he has now taken his helmet off so that looks like the end of his evening.

Nishit asks: "Explain the working of DRS, especially the part where detection of gap between 2 drivers takes place."

The DRS works by opening a flap on the rear wing to reduce drag and boost top speed. The teams can use it any point in practice and qualifying but it is limited in the race. A driver can only use it in certain activation zones that are usually on straights ahead of popular passing places. In order to be able to activate the DRS the driver has to be within one second of the car in front when he goes through the detection point, which is usually before the corner leading on the straight. When he gets into the activation zone he can then reap the rewards of having less drag than his rival. Hope that explains it!

James says: "Correct me if I am wrong, DRS doesn't boost the top speed of an F1 car. The top speed of an F1 car is governed by its 7th gear's rev limit, which is exactly the same whether or not DRS is deployed. What DRS does is reduce the drag on the car like you have mentioned in your answer to Nishit's question and the effect of the decline in drag is that the car will be able to hit the rev limiter quicker as compared to having more drag."

That is true. I was just trying to explain it as quickly and as simply as possible.

Hamilton complains of a gearbox issue. It seems as though he is having problems with downshifts and despite being told to stay out he has now returned to the pits. Vettel, Alonso and Button remain on track on their long runs.

The times at this stage don't mean a huge amount as we don't know the fuel loads, but for what it's worth Vettel is on a similar pace to Button but is not as far through his run. Massa looks a little quicker but there really isn't a huge amount in it.

Alonso is also looking relatively quick and was about 1.5s faster than Hamilton's last lap now that he is back on track.

Deon says: "What's wrong with Ferrari as the Lotus also over taking then in Qualifying pace now..."

Don't read too much into the times. It's a little bit like trying to guess what your Christmas presents are by looking at the size of the box under the wrapping. Ferrari traditionally don't show their true hand until a little later in the weekend.

Deon says: "What's wrong with Ferrari as the Lotus also over taking then in Qualifying pace now..."

Don't read too much into the times. It's a little bit like trying to guess what your Christmas presents are by looking at the size of the box under the wrapping. Ferrari traditionally don't show their true hand until a little later in the weekend.

The session comes to an end with all the cars bar Webber on track. Another interesting session with Red Bull clocking the fastest time. However, the soft tyres did not offer the faster lap times we would usually expect from them so it's anybody's guess. For the record, Vettel is back out on medium compound tyres.

Presumably Vettel will try a practice start on the medium tyres at the end of this session now. What does that tell us about strategy for Sunday?

Vettel does now turn up on the grid with medium tyres for his practice start.

Well that's the end of today's live commentary. I hope you enjoyed it and we'll be back later with all the reaction from the drivers and teams. We'll also be back tomorrow with more live commentary and news from Abu Dhabi so keep checking the site to make sure you don't miss anything.