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It may only be the end of the second Formula One preseason test, but many of the cars are already in midseason form—midseason 2014, anyway.

While the big headline from the final day of the test was Fernando Alonso's high-speed crash (thankfully, his only injury was a concussion), the lap times turned in over the last four days should cause everyone to take notice.

On Sunday, Lotus' Romain Grosjean set a fastest lap of one minute and 24.067 seconds. That time is quicker than both the pole lap and fastest lap from the 2014 Spanish Grand Prix, also held at the Circuit de Catalunya outside Barcelona.

Grosjean's time was set on Pirelli's super-soft tyres, so a direct comparison to the 2014 race is not possible, since the Italian company had its hard and medium compounds there. According to the BBC's Andrew Benson, Pirelli figure the difference between the medium and super-soft tyres could be up to two seconds per lap.

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But Mercedes' Nico Rosberg was less than two-hundredths of a second slower than Grosjean—on medium tyres.

Rosberg's best time of one minute and 24.321 seconds was almost one second faster than his teammate Lewis Hamilton's 2014 pole time of one minute and 25.232 seconds, also set on mediums.

Red Bull's Daniil Kvyat and Sauber's Felipe Nasr were also quicker than Hamilton's 2014 pole time, with Williams' Valtteri Bottas falling just short.

As always, we should be careful about drawing too many conclusions from testing times—particularly in this case, where different tyre compounds can skew the results.

One thing these times do tell us, though, is any speculation that the gap to Mercedes has been closed is premature. Assuming drivers were running similar fuel loads when they set their fastest laps—not necessarily true, but, for the sake of argument, let's go with it—Mercedes are still way out in front.

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Perhaps the best indicator of how fast the Mercedes can be was Rosberg's reaction to his quick lap. When asked about his strong performance, according to Autosport's Ben Anderson and Jonathan Noble, Rosberg responded, "If you say so! Not according to our numbers, not so much when looking at times from other days."

Rosberg elaborated in a team press release, saying:

Today was actually a really difficult day. In the morning the tyres weren't really working properly and then it was so windy out on track until late in the day. It was difficult to understand in the car because every run was different from corner to corner. Depending on where the wind was coming from, the car felt totally different. So it really made testing extremely tough today.

If Rosberg put in that kind of performance on a really difficult day, well...let's just say there is a lot more to come from the defending champions.

But even if the other teams are not catching Mercedes, their performances are improving. That was already apparent in the first test at Jerez, and the test at Barcelona has confirmed it.

Last year, Fernando Alonso complained that "the cars [were] too slow," per Autosport's Noble. By the end of the season, though, the cars were occasionally matching the performance of the 2013 cars—the last ones with V8 engines.

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This year, we should not be hearing similar complaints. There are still four days of preseason testing to come, and engine manufacturers will also have the option to continue developing their power units once the season begins.

When the engines are truly unleashed—possibly later this week at the last test in Barcelona, certainly in three weeks at the first race in Melbourne—who knows what the limit for this year's cars is?

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