Will 'flat-out' Sochi reveal truer 2016 form?

Ferrari and Mercedes fired the first shots in Formula 1's in-season arms race during Friday practice for the Russian Grand Prix, but so far it looks as though all this has done is maintained the established status quo.

The Scuderia fitted new internal combustion engines to Sebastian Vettel's and Kimi Raikkonen's cars, having spent three development tokens to improve the performance of its power units.

Mercedes spent two tokens of its own - to update the fuel systems on Lewis Hamilton's and Nico Rosberg's current power units, as well as those of the customer squads. Petronas has also added new oil this weekend.

Though Rosberg has been pushing the idea that Ferrari hasn't shown its true colours yet this season, following messy races in Australia, Bahrain and China, putting Vettel onto his third of five permitted ICEs for the year already suggests Ferrari knows it has not really been at the races so far.

That preferred customer team Haas will have to wait for this update until the next race in Spain - what Romain Grosjean called "the plan from the beginning" - suggests Ferrari knows it needs to be more aggressive if it really wants to carry the fight to Mercedes.

A glance at the headline laptimes from Friday practice suggests Mercedes has little to be concerned about.

Rosberg led a comfortable Mercedes one-two in the first session and Hamilton was well clear of Vettel's Ferrari in the second, before a suspected electrical/gearbox problem shut Vettel's car down after just 10 laps.

PURE PACE RANKING

1.  Mercedes (Hamilton)        1m37.583s (super-soft)
2.  Ferrari (Vettel)           1m38.235s (super-soft)
3.  Red Bull (Ricciardo)       1m39.084s (soft)
4.  Williams (Bottas)          1m39.185s (super-soft)
5.  McLaren (Button)           1m39.196s (soft)
6.  Toro Rosso (Sainz)         1m39.465s (super-soft)
7.  Force India (Hulkenberg)   1m39.795s (super-soft)
8.  Renault (Magnussen)        1m40.193s (super-soft)
9.  Haas (Grosjean)            1m40.260s (super-soft)
10. Sauber (Nasr)              1m40.740s (super-soft)
11. Manor (Haryanto)           1m41.080s (super-soft)

Hamilton endured a couple of off-track moments before he vaulted to the top of the timesheet, but the 0.652-second gap he ultimately enjoyed was inflated by problems for his nearest rivals.

The reigning world champion complained about a lack of grip on the smooth Sochi asphalt, and indeed many struggled to string quick laps together - or hook them up at all.

But in spite of his messy start Hamilton was the only frontrunner to really put a lap together in FP2.

Vettel was on a better lap before his Ferrari broke down. His best first and second sectors were actually only a few hundredths of a second down on Hamilton's. We never found out how much of the three-tenth deficit in sector three he could have bridged without his problem.

Rosberg had a second stab at a lower fuel run on super-softs, after dropping time to Vettel in all three sectors on his first, but he failed to complete any of them owing to traffic or coming across incidents.

He found at least a tenth in each of the first two sectors, but we don't know how much faster he could have gone in the third because he backed off.

Raikkonen too found it difficult to get the Pirelli tyres working well in relatively cool conditions - something he has struggled with in the past - and he was another 0.343s slower than Rosberg.

But Vettel's efforts suggest Ferrari isn't too far away. We now wait to see if it can stay in the hunt as both of F1's leading teams crank their engines up to full blast in qualifying, though Vettel will ultimately not bear the full fruits of his labours owing to a penalty for an unscheduled gearbox change.

The tyre behaviour - either not fully understanding it or not making the most of the rubber at its best - is certainly playing havoc with the order here.

McLaren's Jenson Button was only fractionally faster on the super-soft compound than he was on the soft, and his soft-tyre lap was better than team-mate Fernando Alonso's super-soft effort.

Red Bull's Daniel Ricciardo, again best of the rest here so far, didn't use the super-soft for any meaningful laps, but was quicker than team-mate Daniil Kvyat (by just over a tenth) and the Williams of Valtteri Bottas using a harder tyre.

"It's very difficult here," said Bottas. "You do a small front wing adjustment in the pits and when you go out you suddenly have massively more grip than in the lap before."

Tyre degradation is low here. The Sochi surface does not seem to tear the tyres up in the same way as others.

The bigger problem is getting the temperatures right for a single flying lap.

Often the fronts are undercooked for the first part of the first flying lap, but much better for the second, only for the rears to then overheat slightly for the latter part of that second lap.

This conundrum is particularly difficult for cars with less downforce overall, on a circuit with some long straightline sections that demand wing be trimmed from the cars in any case.

It seems Mercedes' efficient aerodynamics combined with its power advantage help it achieve a better compromise than most here.

"I had the virtual safety car with a car stopped on track, so that compromised my outlap," added Bottas.

"I couldn't get the tyres ready for the sector one, so I definitely lost some time there, but then sector two and three was good.

"Then the following lap, sector one was good and then sectors two and three were bad.

"I think with a proper outlap without virtual safety car, without traffic, it is possible to get them [super-softs] to work."

But not easy, hence the strange variations (or lack of them) between similar cars using different compounds.

This is the main reason the new Haas team feels it is struggling right now, having been very competitive at the first two races.

Conversely, Renault admitted to being "nowhere" with the tyres in China, but seems to be better off here - faster on shorter runs and more consistent on longer ones, at least with Kevin Magnussen's car.

"It's not one [a track] that suits us very well or is supposed to suit us very well but it doesn't always make sense," said Magnussen.

"We didn't expect it but we're faster, maybe tomorrow we're back like China. We just have to stay focused, improve things where we can and see where we end up."

LONG RUN RANKING (SUPER-SOFT)

1.  Mercedes (Hamilton)       1m41.866s (7 laps)
2.  Williams (Bottas)         1m42.740s (8 laps)
3.  Toro Rosso (Verstappen)   1m42.758s (3 laps)
4.  Ferrari (Raikkonen)       1m42.968s (15 laps)
5.  Force India (Perez)       1m43.752s (11 laps)
6.  McLaren (Alonso)          1m43.790s (7 laps)
7.  Sauber (Nasr)             1m44.277s (10 laps)
8.  Red Bull (Kvyat)          1m44.432s (9 laps)
9.  Manor (Wehrlein)          1m45.232s (7 laps)
10. Haas (Grosjean)           1m45.428s (7 laps)
*Renault did not use the super-soft for long runs

LONG RUN RANKING (SOFT)

1. Williams (Bottas)          1m41.709s (7 laps)
2. Mercedes (Rosberg)         1m42.509s (5 laps)
3. Red Bull (Kvyat)           1m43.030s (5 laps)
4. Toro Rosso (Sainz)         1m43.170s (21 laps)
5. Force India (Perez)        1m43.467s (11 laps)
6. McLaren (Button)           1m43.520s (9 laps)
7. Sauber (Ericsson)          1m44.058s (4 laps)
8. Renault (Magnussen)        1m44.212s (20 laps)
9. Haas (Gutierrez)           1m44.503s (6 laps)

We can see how unusual the order is, though Williams - and Bottas in particular - won't be complaining about that!

It looks as though Rosberg underperformed on the soft tyre, while Kvyat was below par on the super-soft for Red Bull.

Toro Rosso is usually quite effective on Friday long runs, and so it is here, while Haas' struggles are clear for all to see.

Both Force India and McLaren, which tend to struggle relatively on the longer runs, seem in better shape on this track - probably helped by the lack of degradation.

Raikkonen's average time was not spectacular, but he set the fastest of his 15 laps on the super-soft at the end of the run, which contrasts starkly with the mere five laps it took to chew the super-soft to bits at Shanghai last time out.

Ricciardo managed a 19-lap run on the soft in which he set his fastest times at the end too.

"This is a circuit that's quite easy on tyres," reckoned Button. "We're comparing to last year, but compared to every other race this year these tyres are very good. We're able to do a lot of laps on them.

"I think everyone was thinking about, is still thinking about, one or two stops in the race, and probably one."

Hamilton reckons this will amount to a boring race, but it will serve as an indicator of the kind of racing we can expect when the tyres hold up better and drivers are able to push flat out for longer.

It could also give a fairer indicator of where each car stacks up relatively in the overall pecking order, and perhaps how close Ferrari and its new engine may actually be in the ongoing arms race at the front.