One of todays articles on Motorsport.com has some relevance to the discussion:

http://www.motorsport.com/f1/news/analy ... es-864078/
According to an engineer, who did not wish his team to be identified, F1's engines will be at full throttle for** 70** percent of the lap of Barcelona, whereas last year they were at the limit for only **50 **percent.

At the high-speed Monza, simulation data from Magneti Marelli said that 2016 witnessed full throttle for **69 **percent of the lap, whereas this year it could be as high as **80 **percent.

The 2016 Spanish GP was completed in 1:41:40 which is 6100 seconds.

66 laps were done, meaning an average laptime of 92.4 sec. Total time on wide open throttle was therefor 46.2 seconds.

46,2 seconds a lap, times 66 laps is 3049 seconds, which is 50.8 minutes. This is far below the 60 minutes that are possible at WOT at a fuel flow rate of 100kg/h and and allowance of 100kg of fuel.

In 2017 average laptimes will be quicker. If we assume 4sec/lap, then the average laptime is down to 88.4 sec (which means the race is shorter). If they are on wide open throttle for 70% of the lap, that means 61.9 seconds.

61.9 seconds a lap, times 66 laps is 4085 seconds, which is 68.1 minutes. This is above the 60 minutes that are possible at WOT at a fuel flow rate of 100kg/h and and allowance of 100kg of fuel. It is also above the 63 minutes at WOT that is possible with an allowance of 105kg of fuel. Thus, some fuel-saving needs to be done.

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The 2016 Italian GP was completed in 1:17:28 which is 4648 seconds.

53 laps were done, meaning an average laptime of 87.7 sec. Total time on wide open throttle was therefor 60.5 seconds.

60.5 seconds a lap, times 53 laps is 3207 seconds, which is 53.4 minutes. This is far below the 60 minutes that are possible at WOT at a fuel flow rate of 100kg/h and and allowance of 100kg of fuel.

In 2017 average laptimes will be quicker. For Monza, if we assume 2 sec/lap, then the average laptime is down to 85.7 sec. If they are on wide open throttle for 80% of the lap, that means 68.6 seconds.

68.6 seconds a lap, times 53 laps is 3634 seconds, which is 60.6 minutes. This is just above the 60 minutes that are possible at WOT at a fuel flow rate of 100kg/h and and allowance of 100kg of fuel. However, it is below the 63 minutes at WOT that is possible with an allowance of 105kg of fuel.

This does not take pit stops into account, and assumes that the given values in the Motorsport article is for the race, not qualifying. It's pretty clear that races will be more fuel critical in 2017, or that there is less oppurtunity for under-fueling at some races.