This was a very interesting test session. There is absolutely nothing conclusive that can be derived from the test apart from the fact that the top teams are still fast, and the slow teams are still slow.

@Sutton Images

Here are the pointers, as usual.

• Marussia replaced Luiz Razia with Jules Bianchi as Luiz Razia's sponsors didn't pay up. Jules Bianchi is about a second faster than Max Chilton, so this will not be a fun year for the englishman.
• Caterham did nothing interesting, apart from proving James Allison right by removing their illegal exhaust system.
• Torro Rosso, again nothing eventful. It's got average pace. Reliable.
• Force India confirmed Adrain Sutil as their second driver, hence Jules Bianchi went to Marussia. Smart move, as they get to keep Mercedes engine, and McLaren technical support. Bulletproof car, no issues, fast as well.
• Sauber has a fast car, but their reliability wasn't impressive as they suffered small technical glitches during race simulations. Esteban racked up the highest mileage of any driver.
• Williams has a very good car as well, and Bottas thinks they will challenge the front-runners. It's a bit optimistic, but with a Finn in the cockpit, anything can happen.
• Ferrari also has a fast car, the only glitch being that the front wheel fell off once. Ferrari claim it's no biggie. Oh well.
• Lotus has a good car, but concentrated on getting their rear wing stalling device working properly. Kimi had the least running of any driver, with gearbox issues, and food poisoning. He wasn't complaining though. They did a lot of sandbagging. It's a quick car, but their real strength lies in race distance pace, which was impressive. Romain looks a different man. He's much more mature. He will have a good year by the looks of it. 
• McLaren was hard to judge, as they took a lot of time to make setup changes. They're the only team to have a completely new car. Others have simply evolved their 2012 designs. It's definitely very quick, one of the fastest. Reliable as well. They claim to have some trouble understanding the tyres. They said that many times, repeatedly. Something fishy.
• Mercedes set the fastest time of the test, but they did it on a low fuel run, so it's hard to compare with the other teams. Their race simulation timings weren't that impressive though. Very quick in wet conditions though.
• Red Bull rewrote the rules of sandbagging at this test. It's by far the quickest car, and with the most downforce. Good race distance pace as well. But they deliberately hid the cars true pace, and would constantly try to hide their car from photographers. Vettel was frustrated by the lack of low fuel runs, but the team was adamant about hiding their true potential.